Tobacco cessation interventions for young people

  • Review
  • Intervention

Authors


Abstract

Background

Most tobacco control programmes for adolescents are based around prevention of uptake, but teenage smoking is still common. It is unclear if interventions that are effective for adults can also help adolescents to quit. This is the second update of a Cochrane review first published in 2006.

Objectives

To evaluate the effectiveness of strategies that help young people to stop smoking tobacco.

Search methods

We searched the Cochrane Tobacco Addiction Group's Specialized Register in February 2013. This includes reports for trials identified in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and PsyclNFO.

Selection criteria

We included randomized controlled trials, cluster-randomized controlled trials and other controlled trials recruiting young people, aged less than 20, who were regular tobacco smokers. We included any interventions; these could include pharmacotherapy, psycho-social interventions and complex programmes targeting families, schools or communities. We excluded programmes primarily aimed at prevention of uptake. The primary outcome was smoking status after at least six months follow-up among those who smoked at baseline.

Data collection and analysis

Both authors independently assessed the eligibility of candidate trials and extracted data. Included studies were evaluated for risk of bias using standard Cochrane methodology. Where meta-analysis was appropriate, we estimated pooled risk ratios using a Mantel-Haenszel fixed-effect method, based on the quit rates at longest follow-up.

Main results

Twenty-eight trials involving approximately 6000 young people met our inclusion criteria (12 cluster-randomized controlled trials, 14 randomized controlled trials and 2 controlled trials). The majority of studies were judged to be at high or unclear risk of bias in at least one domain. Many studies combined components from various theoretical backgrounds to form complex interventions.The majority used some form of motivational enhancement combined with psychological support such as cognitive behavioural therapy (CBT) and some were tailored to stage of change using the transtheoretical model (TTM). Three trials based mainly on TTM interventions achieved moderate long-term success, with a pooled risk ratio (RR) of 1.56 at one year (95% confidence interval (CI) 1.21 to 2.01). The 12 trials that included some form of motivational enhancement gave an estimated RR of 1.60 (95% CI 1.28 to 2.01). None of the 13 individual trials of complex interventions that included cognitive behavioural therapy achieved statistically significant results, and results were not pooled due to clinical heterogeneity. There was a marginally significant effect of pooling six studies of the Not on Tobacco programme (RR of 1.31, 95% CI 1.01 to 1.71), although three of the trials used abstinence for as little as 24 hours at six months as the cessation outcome. A small trial testing nicotine replacement therapy did not detect a statistically significant effect. Two trials of bupropion, one testing two doses and one testing it as an adjunct to NRT, did not detect significant effects. Studies of pharmacotherapies reported some adverse events considered related to study treatment, though most were mild, whereas no adverse events were reported in studies of behavioural interventions.

Authors' conclusions

Complex approaches show promise, with some persistence of abstinence (30 days point prevalence abstinence or continuous abstinence at six months), especially those incorporating elements sensitive to stage of change and using motivational enhancement and CBT. Given the episodic nature of adolescent smoking, more data is needed on sustained quitting. There were few trials with evidence about pharmacological interventions (nicotine replacement and bupropion), and none demonstrated effectiveness for adolescent smokers. There is not yet sufficient evidence to recommend widespread implementation of any one model. There continues to be a need for well-designed adequately powered randomized controlled trials of interventions for this population of smokers.

Plain language summary

Are there any smoking cessation programmes which can help adolescents to stop smoking

Worldwide, between 80,000 and 100,000 young people start smoking every day and up to one in four UK and American young people smoke. Many adolescent tobacco programmes focus on preventing teenagers from starting to smoke, but some programmes have been aimed at helping those teenagers already smoking to quit. We identified 28 studies of mixed quality (around 6000 participants) that researched ways of helping teenagers to quit. Programmes that combine a variety of approaches, including taking into account  the young person's preparation for quitting, supporting behavioural change and enhancing motivation show promise. The number of trials and participants are beginning to be adequate to provide evidence to judge effectiveness. Medications such as nicotine replacement and bupropion have not yet been shown to be successful with adolescents, and some adverse events have been reported. Trials so far have had different definitions of quitting and many smaller trials did not have enough participants for us to be confident about wider application of the results. Some approaches may be worthy of consideration but there is still a need to provide better evidence before the likely success and costs of large scale service programmes can be estimated accurately.

எளியமொழிச் சுருக்கம்

வளர் பருவத்தினர் புகைப்பிடிப்பதை நிறுத்துவதற்கு உதவக் கூடிய புகைப்பிடிப்பதை விடுவதற்கான சிகிச்சை தலையீடுகள் ஏதேனும் உள்ளதா

உலகளவில், ஒவ்வொரு நாளும் 80,000 மற்றும் 100,000 வரை இடையேயான இளம்வயது மக்கள் புகைக்க ஆரம்பிக்கின்றனர் மற்றும் நான்கில் ஒரு யுகே மற்றும் அமெரிக்க இளம் வயது மக்கள் புகைக்கின்றனர். அநேக வளர் பருவ புகையிலை திட்டங்கள், வளர் பருவத்தினர் புகைக்க தொடங்குவதை தடுப்பதில் நோக்கம் கொண்டுள்ளன, ஆனால் சில திட்டங்கள், ஏற்கனவே புகைத்து கொண்டிருக்கும் வளர் பருவத்தினருக்கு அதை விடுவதற்கு உதவுவதில் நோக்கம் கொண்டுள்ளன. வளர் பருவத்தினர் புகைப்பதை விடுவதற்கு உதவும் வழிகளை ஆராய்ந்த கலவையான தரத்தை கொண்டிருந்த 28 ஆய்வுகளை (ஏறக்குறைய 6000 பங்கேற்பாளர்கள்) நாங்கள் அடையாளம் கண்டோம்.  புகைப்பதை விடுவதற்கு இளம் நபரின் ஆயத்தம், நடத்தை மாற்றத்திற்கு ஆதரவளித்தல், மற்றும் செயல் நோக்கத்தை மேம்படுத்துதல் போன்றவற்றை கணக்கில் கொள்ளும் பலவித அணுகுமுறைகளை இணைக்கும் திட்டங்கள் உறுதிஅளிப்பவையாக உள்ளன. திறனை முடிவு செய்வதற்கு ஆதாரத்தை அளிக்க சோதனைகள் ம் மற்றும் பங்கேற்பாளர்களின் எண்ணிக்கை போதுமானதாக இருக்க ஆரம்பித்து உள்ளன. வளர் பருவத்தினரில், நிகோட்டின் மாற்று மற்றும் பூப்ரோபியான் போன்ற மருந்துகள் வெற்றி மிக்கவையாக காட்டப்படவில்லை மற்றும் சில பாதகமான நிகழ்வுகள் அறிக்கையிடப்பட்டுள்ளன. இது வரைக்குமான சோதனைகள் புகைப்பதை விடுவது என்பதற்கு வெவ்வேறான சொற்பொருள் விளக்கங்களை கொண்டுள்ளன மற்றும் முடிவுகளின் பரந்த அளவிலான செயலாக்கத்திற்கு, நாம் நம்பிக்கையாய் இருக்கும் வகையில் அநேக சிறிய சோதனைகள் போதுமான பங்கேற்பாளர்களை கொண்டிருக்கவில்லை. சில அணுகுமுறைகள் கருத்தில் கொள்ளப்படுவதற்கு தகுதி வாய்ந்ததாக இருக்கக் கூடும், ஆனால், பெரியளவு சேவை திட்டங்களின் சாத்தியமான வெற்றி மற்றும் செலவுகளை துல்லியமாக மதிப்பீடு செய்வதற்கு முன் சிறப்பான ஆதாரத்தை வழங்குவதின் தேவை இன்னும் இருக்கிறது.

மொழிபெயர்ப்பு குறிப்புகள்

மொழிபெயர்ப்பாளர்கள்: சிந்தியா ஸ்வர்ணலதா ஸ்ரீகேசவன், ப்ளசிங்டா விஜய், தங்கமணி ராமலிங்கம், ஸ்ரீகேசவன் சபாபதி.

Streszczenie prostym językiem

Czy istnieją programy antynikotynowe które mogą pomóc nastolatkom w zerwaniu z nałogiem?

Na całym świecie codziennie od 80 tys. do 100 tys. młodych osób osób zaczyna palić, a wśród młodzieży mieszkającej w Wielkiej Brytanii i USA pali nawet co czwarta osoba. Wiele programów antynikotynowych kierowanych do nastolatków skupia się na zapobieganiu rozpoczynania przez nich palenia, jednak celem niektórych programów jest pomoc w zerwaniu z nałogiem tym nastolatkom, którzy już zaczęli palić. Zidentyfikowano 28 badań różnej jakości (obejmujących około 6000 uczestników), w których badano metody pomocy nastolatkom w zaprzestaniu palenia. Programy, które łączą różne podejścia - w tym biorące pod uwagę przygotowanie młodej osoby do zerwania z nałogiem, wspieranie zmian behawioralnych oraz zwiększenie motywacji - są obiecujące. Liczba badań oraz uczestników zaczyna być odpowiednia, aby dostarczyć danych pozwalających ocenić efektywność. Nie wykazano dotychczas skuteczności terapii takich nikotynowa terapia zastępcza oraz bupropion u nastolatków, a jednocześnie zgłaszano zdarzenia niepożądane. Do tej pory w badaniach wykorzystywano różne definicje zaprzestania palenia, a wiele mniejszych badań nie obejmowało wystarczającej liczby uczestników tak, aby zyskać pewność na temat szerszego zastosowania wyników. Niektóre metody mogą być warte rozważenia, jednak nadal konieczne jest dostarczenie lepszych dowodów zanim możliwe będzie dokładne oszacowanie skuteczności i kosztów programów organizowanych na dużą skalę.

Uwagi do tłumaczenia

Tłumaczenie: Bartłomiej Matulewicz, Redakcja: Łukasz Strzeszyński

Summary of findings(Explanation)

Summary of findings for the main comparison. Transtheoretical Model of Change (TTM) for smoking cessation in young people
  1. 1 Assumed risk is average across control groups
    2 All three studies judged to be at unclear or high risk of bias in at least one domain
    3 Small number of total events (>300)

Transtheoretical Model of Change (TTM) compared to standard care or dietary advice for smoking cessation in young people
Patient or population: young people
Intervention: TTM
Comparison: standard care or dietary advice
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Standard care or dietary advice TTM
Cessation
Self-report
Follow-up: 12 months
103 per 1000 1 160 per 1000
(124 to 207)
RR 1.56
(1.21 to 2.01)
1662
(3 studies)
⊕⊕⊝⊝
low 2,3
 
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Summary of findings 2 Interventions including motivational enhancement for smoking cessation in young people

Summary of findings 2. Interventions including motivational enhancement for smoking cessation in young people
  1. 1 Assumed risk based on average across control groups in each study
    2 Large majority of included studies judged to be at high or unclear risk of bias in at least one domain

Interventions including motivational enhancement compared to brief interventions for smoking cessation in young people
Patient or population: young people
Intervention: Interventions including motivational enhancement
Comparison: brief interventions
OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
Brief interventions Interventions including motivational enhancement
Cessation
Majority self report (some biochemical validation)
Follow-up: 6+ months
87 per 1000 1 138 per 1000
(111 to 174)
RR 1.6
(1.28 to 2.01)
2667
(12 studies)
⊕⊕⊕⊝
moderate 2
 
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Summary of findings 3 Not on Tobacco (NoT) programmes for smoking cessation in young people

Summary of findings 3. Not on Tobacco (NoT) programmes for smoking cessation in young people
  1. 1 Majority of studies at high risk of bias in at least one domain
    2 Small number of total events (<300)

Not on Tobacco (NoT) programmes for smoking cessation in young people

Patient or population: young people
Intervention: Not on Tobacco programmes

Comparison: brief interventions

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments
Assumed riskCorresponding risk
ControlNoT
Cessation
Follow-up: 6+ months
104 per 1000 137 per 1000
(105 to 178)
RR 1.31
(1.01 to 1.71)
1420
(6 studies)
⊕⊕⊝⊝
low 1,2
 
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

Background

In much of the developed world, the prevalence of smoking amongst young people has been falling over the last 20 years. Recent figures from the UK show that for 11 to 15 year olds, 25% had tried smoking at least once, the lowest figure since 1982, when the figure was 53%. Currently, around 5% of 11 to 15 year olds are smoking regularly (one cigarette per week or more), roughly half the proportion doing so in 2001 (NHSIC 2011). A similar decline has been noted in the United States, although the rate of decline has levelled off in recent years, attributed to the withdrawal of funding for programmes; in 2011, 25% of high school males and 17% of females smoked tobacco (MMWR 2012). In developing economies the picture is less clear cut, with wide variation and often higher rates of smoking in young people (Eriksen 2012). The incidence of the initiation of smoking first becomes measurable in the 10 to 12 year age range (ONS 2000), and most adult smokers acquired the habit in teenage years (NHSIC 2012). However, there is evidence that within a short time of commencing many teenage smokers want to quit (Burt 1998; Hu 1998; Sussman 1998; Stanton 2001; MMWR 2009). Frequent quit attempts are reported in this population (Stanton 2001; MMWR 2009).

Although the major burden of disease caused by smoking falls on the adult population, there are several reasons why those charged with promoting child health should be active in tobacco control at an appropriate level. Firstly, the vast majority of smokers acquire the habit in childhood and young smokers suffer impairment of lung function and lung growth (NHSIC 2012). There is evidence that those who start earliest have greatest difficulty in quitting, and that they may be more susceptible to disease in adulthood. There is also growing evidence that addiction to nicotine can develop very rapidly in young smokers, making quitting difficult (DiFranza 2008). The tobacco industry have long been aware of the need to replace adult smokers with new young recruits, and there is now strong evidence of the effect that all advertising, including that at point of sale, has on encouraging young people to smoke (CPHTP 2012).

An additional cause for concern is that smoking may be a particular problem in young people with mental health or behavioural problems. In the UK, smoking rates among 11 to 15 year olds were 30% in those with conduct disorder, 19% in those with emotional disorder, and 15% in those with attention deficit hyperactivity disorder (ADHD) compared to 5% in those without such disorders (Green 2004; Geeta 2012).There is now strong evidence that the relationship is causal with respect to depression (Boden 2010), whilst for ADHD molecular genetics would seem to play a role.

There is now a large literature on smoking cessation services for adults. This is reflected in a number of Cochrane reviews examining several aspects of the subject in detail. Many countries have developed appropriate services for adults. However, whilst some have suggested that similar services, suitably modified, should be considered for young people (Raw 1998), this assertion is open to challenge in view of the difference in smoking pattern, lifestyle and attitudes to services in this age group (TAG 2000). Previous reviews of adolescent smoking cessation have been published (Sussman 1999; Sussman 2002; McDonald 2003; Sussman 2006; Patnode 2013); this is the second update of the first Cochrane review to focus on smoking cessation in young people under 20 years. A further systematic review has looked at strategies for smoking cessation for university age smokers (Villanti 2010). The paucity of high quality research evidence to answer important clinical questions is a recurrent theme of reviews in this area.

Other Cochrane reviews of interventions relevant to tobacco addiction amongst young people have mainly focused on primary prevention. These include a review of school-based prevention programmes (Thomas 2012), and reviews of mass media interventions (Brinn 2010), community interventions (Carson 2011), interventions for reducing access by preventing illegal sale of tobacco (Stead 2005), prevention in indigenous youth (Carson 2012), and school smoking policies (Coppo 2012). This review looks at strategies for smoking cessation in young people and more specifically at the context in which the interventions are offered, and how young people are enrolled into quit attempts.

Objectives

To evaluate the effectiveness of strategies that help young people to stop smoking tobacco.

Methods

Criteria for considering studies for this review

Types of studies

Eligible study designs include:
a) Randomized controlled trials (RCTs)
Studies in which individuals, classes, schools, units or groups were randomized to either the intervention or the control arm of the experiment, or randomized to receive different interventions.

b) Cluster-randomized controlled trials (C-RCTs)
Trials that have as the unit of allocation a school or organization level, or where clusters of professionals or groups of professionals are implementing interventions.

c) Controlled trials
We include trials that allocate individuals or units to intervention and control conditions without formal randomization if baseline characteristics were assessed and were comparable. We have assessed the sensitivity of our conclusions to the inclusion of evidence from non-randomized studies.

Types of participants

Participants are young people, aged less than 20, who are regular tobacco smokers. As there is evidence that some young people have an irregular pattern of smoking, for example smoking only at weekends (Grimshaw 2003) or weekly (O'Loughlin 2003), we define a regular smoker in this review as a young person who smokes an average of at least one cigarette a week, and has done so for at least six months. Trials which target young people who smoke less than this were excluded.

If a study included participants beyond our top threshold of 20th birthday (for example,16- to 21-year-olds), we have included the study if the majority of participants were aged less than 20, and if the design of the programme specifically considers the needs of young people.

The intervention may also be aimed at the organization to which the young person is attached. If so, the study design must demonstrate suitable control for differences in the two groups. Only studies with an outcome related to the individual smoker are included.

Exclusions

We exclude from this review Interventions specifically targeting young women in pregnancy, since this topic is covered by the Pregnancy and Childbirth Group (Coleman 2012; Lumley 2009). We also exclude any programme aimed primarily at the adult population, and have contacted investigators where there was a lack of clarity on this issue.

Types of interventions

Interventions could be specifically designed to meet the needs of young people aged under 20 years, or could also be applicable to adults. Interventions could range from simple ones such as pharmacotherapy, targeting individual young people, through strategic programmes targeting people or organizations associated with young people (for example, their families or schools), to complex programmes targeting the community in which young people study or live. We differentiated between these in the analyses.

To be included, all interventions had to be aimed at helping young people to stop smoking tobacco. We included cessation programmes or strategies that also targeted relapse. We included programmes or strategies that targeted psycho-social determinants (for example, enhancing self efficacy for refusing tobacco), or that focused on developing life skills in order to stay abstinent, if the study design was appropriate. No restrictions were placed on the setting in which the intervention was offered (for example, school, hospital, doctor's surgery, or dentist).

Smoking prevention programmes were excluded, even if they reported cessation data, as they have been the subject of previous reviews (Brinn 2010; Carson 2011; Thomas 2012). Within large-scale community primary prevention interventions, health education programmes/curricula or mass media campaigns that target young people, we only considered for inclusion the cessation component of those programmes where the following three criteria were met: that part of the intervention had been specifically designed to target cessation; that the interventions could be separately assessed; and that the interventions explicitly met the criteria of this review for study design and recruitment.

Control conditions

Interventions in the control arm of the study could be one of the following:

  • no intervention;

  • delayed intervention beyond the last date of data acquisition including follow-up;

  • information on stopping smoking either delivered to individuals in control groups or as literature (indicated in Characteristics of included studies as “Brief Intervention”);

  • general tobacco education given to all participants in trial.

Studies that compared two different cessation interventions or combinations of interventions were also included.

We have not included primary prevention strategies that identify and follow up baseline tobacco users, or programmes aimed solely at relapse prevention.

Types of outcome measures

Measures of quitting

The primary outcome of interest was change in smoking behaviour, i.e. being a smoker at baseline and becoming an ex-smoker at post-test for all participants who received the intervention. The primary outcome was smoking status at six months follow-up or longer. Trials with follow-up of less than six months have been excluded. We have not included relapse rates in the review.

We have reported the definition of cessation used in each trial, for example abstinence during a particular period, such as in the past 7 or 30 days (point prevalence), abstinence from the start of the programme (continuous abstinence), or abstinence following occasional relapse in the two weeks post-treatment grace period (prolonged abstinence) (Hughes 2003). If studies reported cessation using more than one definition of abstinence we used the most rigorous outcome. Biochemical confirmation of self-reported non-smoking is generally taken to be the gold standard for reporting of quit rates (West 2005). This tests for the presence of smoking-related substances in exhaled breath, saliva, urine or blood, and is the preferred verification method for reported outcomes where this is available. It should be noted that biochemical validation may not be a very sensitive measure of change in smoking status for irregular smokers; it is possible that some studies may have recruited participants who would not be identified as smokers at baseline.

Enrolment

We analysed data on an intention-to-treat basis, i.e. with all participants analysed in the groups to which they were randomized, and including all the randomized participants. Where necessary we have contacted authors for discrete data if it could not be imputed from the published reports. We have reported enrolment to studies according to type, as revealed in the study designs; e.g. personal invitation, entry through mass media campaigns, non-voluntary interviews in schools, etc. Randomization may be at the level of individual or organization. We have noted whether randomization took place after enrolment into the intervention.

Participation and retention in intervention

Since one might postulate that there is educational benefit from participation in a cessation programme, we report data on losses to follow-up. We have counted drop-outs and losses to follow-up as continuing smokers.

Adverse events

We extracted data on adverse events as a secondary outcome.

Search methods for identification of studies

We used the Cochrane Tobacco Addiction Review Group search strategies to identify randomized controlled trials (RCTs), cluster-randomized controlled trials (C-RCTs), and controlled trials of smoking cessation and prevention interventions. Trials relevant to the review were identified using the free text and keywords 'Child' or 'adolescent*' or 'adolescence'. We searched the Cochrane Tobacco Addiction Group Specialized Register in February 2013. At the time of the search the Register included the results of searches of the Cochrane Central Register of Controlled Trials (CENTRAL), issue 12, 2012; MEDLINE (via OVID) to update 20130104; EMBASE (via OVID) to week 201252; and PsycINFO (via OVID) to update 20121231. See the Tobacco Addiction Group Module in the Cochrane Library for full search strategies and a list of other resources searched. We have also searched the 'grey literature' (unpublished resources and conference proceedings) and the reference lists of identified studies and contacted manufacturers of smoking cessation products. 

Where necessary, we have contacted the authors of existing trials and other experts for ongoing trials, and for unpublished results pertaining to completed trials, subject to the availability of peer review.

We also contacted smoking cessation e-networks with a list of the references to extracted studies, to request verification and any additional information.

Data collection and analysis

Selection of studies

We drew up a prospective list of eligibility criteria with two levels of priority: essential and desirable. Two authors (GG and AS) assessed the retrieved abstracts against this list for possible inclusion, to measure the feasibility of each criterion. We assessed levels of agreement by kappa score.

After piloting, we applied the agreed criteria to the abstracts of all studies extracted from the databases. We then categorized studies into three groups:

  1. Both authors agree on inclusion based on the abstract;

  2. One author suggests inclusion based on the abstract;

  3. Both authors agree on exclusion based on the abstract.

We retrieved full text articles for groups (1) and (2). The processes outlined here and later were used for all updates.

Two authors independently assessed each full article, using the agreed inclusion criteria. For studies where there was disagreement, the editorial base was consulted to reach a consensus. Where there was ambiguity in trial reporting or lack of data, we contacted investigators for clarification where possible. If we could not retrieve missing data, a study may have been excluded on that basis.

Data extraction and management

We extracted and reported the following information, where it was available, concerning each study:

  1. Country and study setting

  2. Theoretical framework (including a brief description of the intervention)

  3. Focus of the intervention

  4. Type of intervention, its duration, intensity, delivery format, gatekeeper

  5. Length of follow-up

  6. Size of eligible population

  7. Recruitment rate

  8. Number of participants or number of clusters and participants

  9. Definition of the study population

  10. Age range, grade, gender and ethnicity of participants

  11. Definition of smoking status used at baseline

  12. Definition of abstinence

  13. Biochemical validation

  14. Adverse effects of intervention

We report any threats to validity or other limitations described by the studies and report where authors have been contacted for discrete data in the 'notes' section (see Characteristics of included studies).

We have maintained a full list of excluded studies (see the Characteristics of excluded studies).

Assessment of risk of bias in included studies

We rated each included study as being at low, unclear, or high risk of bias in five domains:

  1. Random sequence generation

  2. Concealment of allocation. For cluster-randomized controlled trials which recruited after allocation to intervention or control status, we took account of whether individuals may have been selectively recruited or may have differentially refused to participate in the light of the known allocation, where this could be ascertained (Campbell 2004a; Campbell 2004b; Hahn 2005).

  3. Performance bias (blinding of participants and personnel, if applicable)

  4. Detection bias (blinding of outcome assessment, biochemical validation)

  5. Attrition

We also recorded any other risks of bias that did not fit in the above categories.

Measures of treatment effect

We summarised an effect size for each individual study as a risk ratio (RR) with 95% confidence intervals, and these are displayed in Analysis 1.1 for descriptive purposes. The risk ratio is calculated as (number quit in intervention group/ number randomized to intervention) / (number quit in control group/ number randomized to control), with participants randomized but lost to follow-up regarded as non-abstinent.

Unit of analysis issues

For cluster randomized trials, we checked whether the analysis used the same unit as randomization, or if other methods were used to account for cluster effects, such as multi-level modelling. We either included data that had been corrected or considered whether it was possible to adjust odds ratios. Unadjusted results are reported as such.

Data synthesis

We have pooled groups of studies that we consider to be sufficiently similar in their interventions, comparison groups, setting, and participants, provided that there was no evidence of substantial statistical heterogeneity as assessed by the I² statistic (Higgins 2003). We estimated a pooled risk ratio using the Mantel-Haenszel fixed-effect model, based on the quit rates at longest follow-up. Where meta-analysis was not appropriate, we present summary and descriptive statistics.

Results

Description of studies

Results of the search

For this update 64 references were identified, and four new trials were added to the included studies. These include one trial previously awaiting classification, which tested two different interventions so is treated as two trials in the analyses (Joffe 2009; NoT MD 2009). Figure 1 displays the numbers of records screened and studies included in previous versions of the review. The 90 excluded trials are listed in the Characteristics of excluded studies table with reasons for their exclusion, and the characteristics of two ongoing studies can be found in the Characteristics of ongoing studies table. One previously ongoing study was published in full after the date of search so is in the Characteristics of studies awaiting classification table.

Figure 1.

Study flow diagram

Included studies

Full details of the included studies are given in the Characteristics of included studies table where new trials are identified in the notes as "New for 2013 update".  Trials are identified by the first author and the publication year of the main report, except for a group of studies reporting the Not on Tobacco (NoT) programme and the Project X programme, which are identified by programme type, trial location, and publication year of the main report.

Theoretical basis of intervention

It was difficult to stratify studies into categories with respect to the nature of the intervention. One intervention, conducted in 1978, used the health promotion strategies of that period (Greenberg 1978). Another used personal health risk management (Chan 1988). However, many interventions were complex and used combinations of psycho-social theories (see Sheppard 2009 for discussion of management of reviews of complex interventions). Constructs relating to motivational enhancement and strategies for resisting cultural and social pressures were the most common. Studies of this type included those using Motivational Interviewing, such as Colby 2005, Peterson 2009 and Horn 2007, sometimes combined with some form of relapse prevention advice and ongoing support (Brown 2003; Robinson 2003; Lipkus 2004). Other studies tested interventions based on the Transtheoretical Model of Change for adolescents (Prochaska 2000), either alone (Aveyard 2001) or in combination with other modalities, including brief advice and motivational enhancement (Hollis 2005) and cognitive behavioural therapy (CBT) (Lipkus 2004). Myers 2005 used an intervention based on CBT and motivational enhancement, while two other studies (Project EX-1 2001 and Project EX Russia 2013) used a more eclectic mix which included yoga and meditation. Studies of NoT used social cognitive theory (NoT FL 2001; NoT NC 2002; NoT WV 2004; NoT AL 2008; NoT MD 2009; NoT WV 2011). Three further studies have been undertaken based, at least in part, on social cognitive learning models (Patten 2006; Woodruff 2007; Peterson 2009). Three were primarily Information and Communication Technology (ICT) based interventions (Aveyard 2001; Patten 2006; Woodruff 2007). Finally, three studies have explored pharmacological support for quitting (Killen 2004; Moolchan 2005; Muramoto 2007).

Recruitment and settings

As can be expected from a cohort where most are still associated with some form of formal education, recruitment for studies was mainly within an educational setting (Greenberg 1978; Chan 1988; Aveyard 2001; NoT FL 2001; Project EX-1 2001; NoT NC 2002; Robinson 2003; Killen 2004; NoT WV 2004; Kelly 2006; Woodruff 2007; Hoffman 2008; NoT AL 2008; Joffe 2009; NoT MD 2009; NoT WV 2011). Educational settings have the advantage of easier recruitment and minimization of contamination. Six studies recruited from the healthcare environment (Brown 2003; Colby 2005; Hollis 2005; Moolchan 2005; Myers 2005; Horn 2007). Two studies (Lipkus 2004; Patten 2006) recruited directly from the community. Typically, where school or college was the base, the trials were clustered and the intervention was delivered to all students in one school, with matched schools used for control (Aveyard 2001; NoT studies; Project X studies; Woodruff 2007). All trials but two (Aveyard 2001 in the UK and Kelly 2006 in Australia) were based in North America. The rate of recruitment was commented on by several trialists. Where schools were recruited and matched or randomized (Greenberg 1978; Aveyard 2001; NoT studies; Project EX-1 2001; Project EX Russia 2013) and attendance in the programme was not compulsory, typically fewer than half of the students who smoked showed interest in enrolling. It should be noted, however, that for many of these studies parental permission was a requirement. Inducements to enrol and to remain in the study were also a feature of these trials (Greenberg 1978; Project EX-1 2001; Killen 2004; Lipkus 2004; Colby 2005; Moolchan 2005; Myers 2005; Woodruff 2007; NoT AL 2008). In three trials some element of compulsion was present (Brown 2003; Robinson 2003; Myers 2005), either with attendance as a consequence of a smoking policy violation (Robinson 2003) or as a controlled regimen in a hospital setting (Brown 2003; Myers 2005). One trial used a hospital emergency room to identify higher risk teens (Horn 2007).

Definition of smoking

One of the crucial issues for smoking cessation research for young people is how smoking is defined, and how cessation is defined and verified. The cessation issues are dealt with in the Risk of bias in included studies section and in the Discussion section. There was diversity among the included studies concerning the definition of smoking status, with most studies relying on self-reported smoking status at recruitment.  

In general at least one cigarette per week (cpw) was used as a definition of being a smoker.  Many studies used different definitions (e.g. one cigarette per day at recruitment). Where there was doubt we assured compatibility with our criterion through discussion with authors. Hollis 2005 differentiated between smokers and 'experimenters', but no studies explicitly took account of the episodic nature of adolescent smoking (Corby 2000; Grimshaw 2003). Many studies estimated nicotine dependence using some form of scale, most commonly the modified Fagerstrom Questionnaire (Prokhorov 2000; NoT FL 2001; Project EX-1 2001; NoT NC 2002; Brown 2003; NoT WV 2004; Killen 2004; Lipkus 2004; Moolchan 2005; Myers 2005).

Measurement of outcomes

The primary outcome of all interventions was smoking cessation for each individual. Just as a wide variety of definitions of smoking were used so there were several definitions of cessation.

The gold standard outcome of continuous abstinence (West 2005) was used by two authors (Lipkus 2004; Peterson 2009). Other continuous measures included 90-day abstinence (Myers 2005) and "prolonged abstinence" (Moolchan 2005).

Point prevalence measures were in the majority and these ranged from cessation for longer than one day (NoT FL 2001; NoT NC 2002; NoT WV 2004; Hoffman 2008) to 30 day cessation (Chan 1988; Aveyard 2001; Project EX-1 2001; Hollis 2005; Kelly 2006; Project EX Russia 2013). The most common outcome measure was seven-day point prevalence (Aveyard 2001; Brown 2003; Robinson 2003; Killen 2004; Lipkus 2004; Colby 2005; Moolchan 2005; Myers 2005; Muramoto 2007; NoT AL 2008). One study defined cessation as two sequential reports of seven-day point prevalence at four months and eight months from the start of the intervention (Lipkus 2004).

Verification of smoking status

Of the 28 studies which satisfied the inclusion criteria for this review, only 14 used or attempted some form of biochemical verification of self reports of smoking status for the whole cohort or for the full duration of follow-up (West 2005). Five trials used more than one method of biochemical verification (Brown 2003; Killen 2004; Colby 2005; Moolchan 2005; Myers 2005). Carbon monoxide levels were measured in eleven trials (NoT FL 2001; NoT NC 2002; Brown 2003; Killen 2004; Colby 2005; Moolchan 2005; Myers 2005; Patten 2006; Horn 2007; Muramoto 2007; NoT WV 2011), and salivary cotinine in ten trials (Brown 2003; Killen 2004; Lipkus 2004; Colby 2005; Moolchan 2005; Myers 2005; Hoffman 2008; NoT AL 2008; Joffe 2009; NoT MD 2009). In Chan 1988 and Myers 2005, smoking status was confirmed by report of another individual, and Peterson 2009 used internal verification within questionnaires.

Risk of bias in included studies

Figure 2 summarises review authors' judgements across each risk of bias domain. The majority of studies were judged to be at unclear or high risk of bias in at least one domain.

Figure 2.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Allocation

Of the 28 studies included studies, 12 allocated groups or institutions to conditions (Chan 1988; Aveyard 2001; NoT FL 2001; Project EX-1 2001; NoT NC 2002; NoT WV 2004; Woodruff 2007; NoT AL 2008; Hoffman 2008; Peterson 2009; NoT WV 2011; Project EX Russia 2013) and 16 allocated individuals (Greenberg 1978; Brown 2003; Robinson 2003; Killen 2004; Lipkus 2004; Colby 2005; Hollis 2005; Moolchan 2005; Myers 2005; Sherbot 2005; Kelly 2006; Patten 2006; Horn 2007; Muramoto 2007; Joffe 2009; NoT MD 2009). Of the cluster-randomized trials, seven were judged to be at high risk of selection bias either because groups or institutions were not randomly allocated or because of the way in which students within clusters were recruited (Chan 1988; NoT FL 2001; NoT NC 2002; NoT WV 2004; Woodruff 2007; NoT AL 2008; NoT WV 2011). Four of the individual studies were rated at high risk of selection bias because of the method of allocation or concealment (Greenberg 1978; Brown 2003; Myers 2005; Sherbot 2005). Fifteen studies did not provide sufficient detail on randomization and allocation, and hence were judged to be at unclear risk of selection bias.

Blinding

The majority of studies were judged to be at unclear risk of performance bias, as it was not clear if blinding had taken place and, in the case of behavioural interventions, was not clear if participants in control groups were aware of the programme the intervention arms were receiving. Nine studies that involved face-to-face contact in the intervention group did not employ any form of biochemical validation, and were hence judged to be at high risk of detection bias due to possible differential misreport.

Incomplete outcome data

One marked feature of all included studies was the effort required to follow-up cases. Losses to follow-up ranged from less than 10% to more than 50% of the cohort. Three studies were judged to be at high risk of attrition bias as over half of the participants were missing data at follow-up (NoT FL 2001; Horn 2007; NoT AL 2008). A further three studies were judged to be at unclear risk as attrition rates were not reported in sufficient detail with which to judge (NoT NC 2002; Robinson 2003; NoT WV 2004). All other studies were judged to be at low risk of attrition bias.

It is a frequent feature of analysis of smoking cessation studies that cases lost to follow-up are assumed to be still smoking. Several authors attempt to discuss this issue and make adjustments in analysis (NoT FL 2001; NoT NC 2002; NoT WV 2004; Hollis 2005; Joffe 2009). As these studies cover those aged 20 or less, it can be assumed that, amongst other issues, this is a mobile population, changing or leaving school, moving on to college, etc. Paradoxically, there may be real pressures to conceal quit attempts from social groups. Several trials analysed their data on an intention-to-treat basis, i.e. including all participants in the groups to which they were originally randomized, and classifying those lost to follow-up as continuing smokers. One other feature of reporting was a tendency to report outcomes as percentages, sometimes without any particular clarity as to the denominator. Some of the results of our analysis have been imputed from percentage data, and in all cases authors have been contacted to ask for verification of the calculations (Chan 1988; NoT FL 2001; Project EX-1 2001; NoT NC 2002; NoT WV 2004; Brown 2003; Killen 2004; Lipkus 2004; Colby 2005).

Other potential sources of bias

We also evaluated studies for any other potential sources of bias. Three studies were judged to be at unclear or high risk of other bias due to possible or confirmed issues with treatment fidelity and contamination (Chan 1988; Aveyard 2001; Robinson 2003). One study was judged to be at high risk of other bias due to significant between group differences at baseline (Sherbot 2005). Finally, one further study was judged to be at high risk of other bias due to a doubling of the control group quit rate between 6 and 15 month follow-ups, which the authors speculate may represent confounding due to the influx of prevention initiatives delivered statewide during that period as a result of funds from the Master Settlement Agreement (NoT WV 2004).

Effects of interventions

See: Summary of findings for the main comparison Transtheoretical Model of Change (TTM) for smoking cessation in young people; Summary of findings 2 Interventions including motivational enhancement for smoking cessation in young people; Summary of findings 3 Not on Tobacco (NoT) programmes for smoking cessation in young people

Smoking cessation

Details of individual study outcomes are given in Analysis 1.1, in subgroups by the definition of abstinence used. Studies that reported more than one definition appear in each applicable subgroup. Four trials reported sustained or prolonged abstinence for at least six months, eight trials reported 30 day point prevalence abstinence and six trials used seven day point prevalence abstinence (PPA) as the strictest outcome. Eight other trials reported cessation that could be based on an even shorter period, or were unclear about the definition. One study is not displayed because we were unable to establish the denominator and the study report was published before follow-up was complete (Robinson 2003). Analysis 1.2 displays the results of trials added for the 2013 update. The wide confidence intervals for individual studies reflect the lack of power due to the small size and low quit rates in many trials. In total, around 6000 young people participated in the included studies.

Studies including Transtheoretical Model of Change (TTM)

Four studies were based on interventions targeting the stage of change of individual participants using TTM. A school-based intervention using a TTM computer expert system (Aveyard 2001) had a risk ratio (RR) for 30 day PPA of 1.45 (95% confidence interval [CI] 1.01 to 2.08) at 12 months, and 1.14 (0.78 to 1.66) after 24 months. By contrast the 'Teen Reach' study (Hollis 2005) included a brief clinical message and motivational counselling and booster sessions as well as using a TTM-based computer expert system recruiting from family practices and paediatric departments. The 'Teen Reach' intervention was effective for smokers (a subgroup of those recruited), with an RR of 1.80 (1.19 to 2.71) at 12 months and the intervention effect persisted with an RR of 1.71 (95% CI 1.06 to 2.76) at 24 months. Hoffman 2008 used a programme of Cognitive Behavioural Therapy (CBT) tailored to stage of change. The measures of quitting on this programme were defined as no smoking during 24 hours prior to interview and verification was attempted although administration proved problematic. The results from this trial do need consideration alongside the known nature of episodic smoking reported by teens.

Pooled results from these three trials show a significant effect in favour of the intervention (at 12 months, RR 1.56, 95% CI 1.21 to 2.01, Analysis 2.1, Summary of findings for the main comparison), yielding a number needed to treat of 17.5 at the end of the first year after the beginning of the intervention. In the two trials with follow-up at two years, the direction of the effect remained consistent but results were no longer statistically significant, with a pooled RR of 1.33 (95% CI 0.99 to 1.79, Analysis 2.2) and a doubling of the number needed to treat.

Lipkus 2004 used a TTM-based intervention that also included motivational enhancement via telephone and cognitive behavioural therapy (CBT) for young people recruited in the community (shopping malls and an amusement park). At eight month follow-up, the hypothesis that telephone counselling as an adjunct to self-help material would be effective was not supported (RR 1.10, 95% CI 0.74 to 1.62) for seven-day PPA. As this trial was testing mode of delivery rather than stage of change, we have not included it in the pooled analysis with the other TTM-based trials. It should be noted that this study was one of the few included in this review which attempted to measure sustained quitting between two points of data collection (four months and eight months).

Psycho-social interventions

Twelve studies used some form of motivational enhancement for young people within their intervention (Figure 3, Analysis 3.1, Summary of findings 2). Point estimates of effect ranged from 0.85 (in a trial with just two quitters, Horn 2007) to 6.00 (Greenberg 1978). Confidence intervals were wide and many trials were small, with only half enrolling more than 50 participants per trial arm (Project EX-1 2001; Brown 2003; Lipkus 2004; Hollis 2005; Peterson 2009; Project EX Russia 2013). Only Hollis 2005 detected a significant effect. Pooled results detected a significant effect in favour of the intervention (RR 1.60, 95% CI 1.28 to 2.01, n = 2667, Analysis 3.1). Two of these studies (Lipkus 2004; Myers 2005) met Russell standards (West 2005) and these have been analysed as an additional subgroup (Analysis 9.1); pooled results were not statistically significant (RR 1.18, 95% CI 0.80 to 1.72). Six studies within the motivational enhancement group used complex interventions that included motivational interviewing as one of their theoretical frameworks. Brown 2003 was based in an inpatient psychiatric facility, Colby 2005 was based in a hospital outpatients and emergency room, Sherbot 2005 recruited from a pool of teenagers identified as having substance misuse issues, Project EX-1 2001 and Peterson 2009 were school based, and Project EX Russia 2013 was based in a youth camp. Although when pooled the six interventions that included Motivational Interviewing as one component of the intervention had a significant effect (RR 1.88, 95% CI 1.30 to 2.72, Analysis 3.2), it would be unwise to draw any inferences from this finding, as not all trials studied Motivational Interviewing alone.

Figure 3.

Analysis 3.1 Motivational enhancement versus brief interventions, cessation at 6 months or longer.

Thirteen studies included cognitive behavioural techniques (Analysis 4.1). This analysis is included as a record of where CBT has been included in trials. It is not possible to pool data from trials using CBT as, in general, CBT was only one component of a multicomponent intervention and the impact of the CBT element is impossible to disaggregate. This impact of this specific technique would, however, be interesting to explore as one study using a combination of CBT and motivational techniques delivered over four sessions with telephone follow-up did not detect any effect on cessation (Robinson 2003). A brief summary of the range of complex interventions is shown in Analysis 5.1.

Greenberg 1978 explored three educational approaches: fact-based, scare-based and attitudinal (values and affective strategies), but differences between the small groups were not statistically significant. Health Risk Assessment (HRA) was trialled by Chan 1988 amongst university students. This study recruited only 40 smokers to the group contributing to this review and did not detect a difference between HRA with feedback and HRA without feedback (RR 4.43, 95% CI 0.59 to 33.50 at nine months).

In some studies there was a degree of externally applied motivation to quit smoking. In Brown 2003, the inpatient adolescents were prohibited from smoking during hospital admission. The Myers 2005 cohort were obliged to attend group quit sessions, although they could decline to be followed up. The Robinson 2003 cohort were referred because of a violation of a local no smoking policy, and reduced punitive sanctions were offered if they attended groups in addition to monetary inducements.

Not on Tobacco (NoT) interventions

The Not on Tobacco intervention (NoT) has been tested in five localities with 1420 smokers in 148 schools (NoT FL 2001; NoT NC 2002; NoT WV 2004; NoT AL 2008; NoT MD 2009; NoT WV 2011). The RRs of the individual trials and overall effectiveness are summarized in Analysis 6.1 (see Figure 4 and Summary of findings 3). Individually, none of the six trials of the NoT intervention demonstrated a statistically significant effect at six months follow-up using an intention-to-treat analysis (raw data supplied by the authors). This may be related to the low power of the individual trials; when the trials are pooled, the result shows a statistically significant effect (RR 1.31, 95% CI 1.01 to 1.71), though the confidence interval is close to the line of no effect. Two new trials of the NoT intervention have been added in the 2013 update (NoT MD 2009; NoT WV 2011). These new trials use outcome measures designed to show persistence of intervention effect beyond measures in previous trials, thereby correcting for one of the difficulties of estimating effectiveness from previous reports, given the episodic pattern of teen smoking. Recent NoT trials have broadly confirmed previous results and it should be noted that length of abstinence measured has been extended in recent work to be in line with Russell Standards (NoT MD 2009; NoT WV 2011).

Figure 4.

Forest plot of comparison: 5 NoT (Not on Tobacco), outcome: 5.1 Cessation at 6 months or longer.

In addition to comparing the standard NoT intervention to control, NoT WV 2011 involved a third arm in which the NoT programme was augmented with a physical activity component (NoT+Fit). At six months, the NoT+Fit arm had significantly higher quit rates when compared with control (RR 1.97, 95% CI 1.02 and 3.79, Analysis 6.2) but the result was not significant when compared with NoT alone (RR 1.48, 95% CI 0.88 to 2.48, Analysis 6.3).

Interventions using ICTs

In settings where all teens have equal access to the Internet and/or computers it has been possible to design studies that include this medium. Four studies utilise ICTs to deliver part of the intervention. Aveyard 2001 and Hollis 2005 used programmes specifically tailored to stage of change, Patten 2006 tested a home-based internet programme based on Social Learning Theory, and Woodruff 2007 used the internet to disseminate a smoking educational package based in a virtual reality. No study relied solely on ICTs. Aveyard 2001 and Hollis 2005 detected significant evidence of an effect, whereas the other two studies did not detect a significant difference between intervention and control arms (see Analysis 7.1; Analysis 7.2; Analysis 7.3).

Pharmacological interventions

This review contains three studies exploring different pharmacological interventions, which we have not pooled. Effect sizes are displayed in Analysis 8.1. All studies were relatively small and abstinence rates were low, hence confidence intervals are wide. One study investigated the effectiveness of nicotine replacement therapy (NRT) in supporting cessation (Moolchan 2005), one tested bupropion as an adjunct to NRT (Killen 2004) and one tested bupropion alone at two strengths: the standard daily dose of 300 mg or a single daily dose of 150 mg (Muramoto 2007). Comparing NRT patches and gum with placebo (Moolchan 2005), results at six months were not statistically significant in this underpowered study, with an RR of 4.12 (95% CI 0.92 to 18.52) for patches and an RR of 1.74 (95% CI 0.34 to 9.00) for gum versus placebo using biochemically verified seven-day PPA. Results using prolonged abstinence also did not detect a significant effect of either type of NRT. Muramoto 2007 did not detect evidence for a benefit of standard dose bupropion (RR 1.49 95% CI 0.55 to 4.02) or a lower 150 mg dose (RR 0.33 95% CI 0.07 to 1.58). Killen 2004 also failed to detect an effect for bupropion used as an adjunct to NRT patches (RR 1.05 95% CI 0.41 to 2.69). The evidence regarding the effectiveness of the use of bupropion alone in adolescence from the single study conducted so far appears to suggest that this intervention does not have a persistent effect (six months or longer) for either of the doses tested.

Adverse effects

No adverse effects were reported in any of the psycho-social trials. In the trial of bupropion as an adjunct to nicotine patch (Killen 2004), although young people reported a total of 47 self-rated 'severe' complaints with nausea the most common, none of these were judged to be severe by the lead study physician. In the trial of nicotine patch versus nicotine gum (Moolchan 2005), active medication was associated with a statistically significant (P > 0.01) increase in four symptom categories, including sore throat, erythema, pruritus and shoulder/arm pain.  In the trial of bupropion alone (Muramoto 2007), four percent of participants reported adverse effects and eight subjects discontinued treatment because of adverse events.  Two serious adverse events resulting in hospitalisation occurred in this trial: one participant was admitted for anticholinergic crisis after ingesting Datura innoxia and one participant intentionally overdosed on study medication and other substances.

Discussion

For the purpose of this review, we have taken a clinical focus on young smokers. In public health terms, the line between young smokers, experimenters and 'potential' smokers is blurred. Some interventions are therefore aimed at the population level, attempting to combine prevention and cessation. Individual clinicians, however, face a different problem: what advice should they give and what works for the young person who has started smoking and expresses a wish to stop? For this review, therefore, we drew what might otherwise be seen as an arbitrary line and developed a protocol which would include those prevention studies that had a cessation intervention component and discrete results for smokers (Chan 1988; Aveyard 2001; Hollis 2005).

Ideally, we would wish to know outcomes in terms of true smoking cessation, i.e. quitting smoking and not returning to the habit, although an absolute measure of cessation in these terms is in practice impossible, as it would require life-long follow-up of subjects. It is necessary therefore to consider just how well what are effectively proxy measures correspond to the desired outcome. Clearly, longer periods of follow-up will be of greater value. We therefore limited our review to studies with six months follow-up, as recommended elsewhere (Mermelstein 2002; West 2005). There is clear evidence in some of the included studies that have done repeated measures of a waning effect over this period (e.g. Myers 2005 and Brown 2003). Early relapse is an obvious danger, especially for young people who have been shown to make many quit attempts (MMWR 2009). In order to standardize comparisons, we took the six month period as beginning from baseline measurement. It should be noted however, that studies may not set a quit date until some weeks into the programme (e.g. Project EX) and this may be a source of bias when comparing outcomes.

A more substantial weakness in the evidence base springs from the definitions of quitting used in studies. These vary from self-reported quitting longer than one day (NoT FL 2001; NoT NC 2002; NoT WV 2004) through to seven-day or 30-day point prevalence abstinence (PPA) at the point of ascertainment, to longer or continuous periods (see Effects of interventions and forest plots). With respect to the shorter PPAs, a negative result is useful in demonstrating evidence of a lack of effect where the study size is adequate but care should be taken with the shorter quit lengths such as 24 hours. The irregularity and instability of the smoking habit in its early stages (for example, weekend smoking is commonly reported) and the low number of cigarettes smoked at baseline by some subjects, call into question the prognostic value of short-term PPA measurements of less than 30 days. Several trials recognize this pattern of smoking and use a 30 day measure of abstinence but  continuous abstinence remains the important and recommended outcome (West 2005). It is tempting to conclude that encouraging an increased number of what are effectively short-lived (e.g. seven-day) quit attempts allows young people to 'practice' quitting, and therefore may help to achieve prolonged cessation in the long run. Prolonged quit attempts might also have a health benefit of their own, or interrupt the progression to more regular or heavy smoking. However, we have no data for young people against which we can test these assumptions.

For our results, we have used an intention-to-treat analysis, i.e. all those randomized included in their original groups, whether or not they received the full intervention. We counted all those with missing data as continuing smokers. We requested information from authors where necessary to facilitate these calculations. Although this is standard practice in adult cessation studies, our review demonstrates that the reasons for young people dropping out from follow-up are diverse, and by no means always related to risk of continued smoking (NoT FL 2001; NoT NC 2002; NoT WV 2004; Hollis 2005). We accept, therefore, that this assumption leads to a conservative analysis, and that it may bias our results towards the null. Unfortunately, there does not seem to be any other way of reliably imputing missing data across all situations, so this problem would seem to be intractable.

Several studies clearly demonstrate the importance of biochemical verification (Robinson 2003; Killen 2004; Colby 2005) as substantial numbers of subjects have given false information regarding quit attempts. This raises possible doubts about the validity of those studies which showed positive results but did not use verification, e.g. Hollis 2005. In Project EX-1 2001, verification was incomplete and a weighting factor was added to results. For NoT WV 2011, verification was added to the intervention but only done at three months. There is a continued need for further studies where smoking status has been verified, but the experience of Kohler (NoT AL 2008) and Hoffman (Hoffman 2008) underline the challenges that face researchers in this area. Muramoto warns that exhaled CO has a short half life and may be an insensitive measure given the episodic nature of teen smoking.  She reports cotinine confirmed rates 50 to 65% lower than CO rates.

With regard to the limitations of the pharmacotherapy trials (Killen 2004; Moolchan 2005; Muramoto 2007), the existing evidence base gives us no reason to believe that the neuropharmacological efficacy, effectiveness and safety of pharmacotherapies for smoking cessation would be different for adolescents than for any other group of smokers. However, the context and meaning of smoking in adolescence is very different from that for adult smokers (Amos 2006), and there is currently insufficient evidence to determine whether NRT aids quitting in adolescents. The evidence on bupropion however appears to suggest this is not effective alone and varenicline is not currently licensed for under 18 years old in UK.

Several of the studies we reviewed appear underpowered as demonstrated by wide confidence intervals (e.g. Greenberg 1978; Chan 1988; Colby 2005; Sherbot 2005; Myers 2005; Horn 2007; Project EX Russia 2013), whilst Moolchan 2005 was powered for smoking reduction outcomes rather than cessation. Overall, the total number of young people currently contributing to this review is around 6000, a very small number considering the low quit rates and the range of interventions under investigation.

It should be noted that where recruitment was by inclusion from self reports it is likely that those volunteering, and in some trials obtaining parental consent, could be perceived as a subset of all smokers - those willing to quit. Some authors comment on this aspect of recruitment (Kealey 2009b). 

The results of this review are consistent with other reviews in this area, though other reviews are very different from ours (Sussman 1998; Sussman 2002; McDonald 2003; Sussman 2006; Gervais 2007). Wherease other reviews had a much wider focus and included non-experimental studies, our review has aimed to evaluate where possible the experimental evidence for effectiveness rather than the more discursive evaluation of current approaches undertaken by other authors. Our results are also consistent with Riemsma 2003, whose review found results similar to Aveyard 2001. A recent review by Patnode et al was limited to interventions relevant to primary care and did not find any evidence of effectiveness (Patnode 2013).

With the exception of two very small trials (Greenberg 1978 and Chan 1988), all the included studies have been published within the last twelve years, suggesting an increase in both activity and quality. We are aware there is a growing interest in this topic and we intend to continue regular updates of this review.  Over the period we have been extracting data, teen prevalence figures have shown some improvement in those countries using global public health campaigns, such as bans on smoking in public places, suggesting global measures may have had an impact on smoking initiation. In some developing countries, however, the prevalence is rising and concern for teens remains.

Authors' conclusions

Implications for practice

There is currently little evidence on effectiveness of pharmacotherapies or incorporation of NRT into psycho-social programmes in this age group. The evidence does not support the use of bupropion either alone or as an adjunct to NRT.  Evidence from one study suggests a mandatory intervention for those caught in violation of school smoking cessation policies is ineffective.

The evidence of outcomes on the Not on Tobacco (NoT) programme is improving and there is better evidence of the effectiveness of this programme in terms of length of abstinence.  The meaningfulness of the definition of cessation (one day or more) used for many of the older NoT trials must be challenged when compared to the episodic nature of patterns of smoking of young people but newer studies are encouraging. 

Those interventions with positive outcomes, in terms of their own protocols, are complex and are designed to respond to the many issues that characterise young persons' smoking. In particular, complex approaches show promise and show some persistence of abstinence (30 days point prevalence or longer) and recent publications add weight to interventions combining motivational enhancement and support with approaches based on social cognitive theory.  A recent trial demonstrates that attention to recruitment and the mode of delivery and follow-up may be as important as the construct for the intervention. However, complex interventions often contain components requiring one-to-one (or one-to-few) input from trained staff, raising the cost of delivery, and means of communication other than face-to-face may be more cost effective. Within the context of a clinical trial, great attention is paid to quality management of the intervention. The challenge for services is to maintain these levels of clinical effectiveness.  In view of the paucity of the current evidence, services should recognize the need to maintain rigorous evaluation in terms of outcomes; many of the issues researchers encountered did not arise simply from research protocols but from the practicalities of working with organisations and young people (Grimshaw 2003; Kishnuck 2004; NoT WV 2011).  There is not as yet sufficient evidence to recommend widespread implementation of any one model.

Implications for research

Research is developing and increasingly studies are measuring verified, sustained quitting. This trend is to be encouraged for all new trials for teen smoking. The evidence is developing for complex psycho-social interventions but needs to be replicated and tested in different settings. The role of motivation to quit and other variables in predicting cessation need to be further explored as do the most appropriate ways of combining readiness to quit into complex programmes. Trials of brief interventions or self-help materials would be useful, particularly as these are often used as control conditions for more complex interventions. Further studies of appropriate ways to use pharmacotherapy in adolescent populations are needed (adequately powered for cessation).

In the six years since this review was first published, few trials have been able to implement suggested standards (Mermelstein 2002; West 2005).  Funders of future trials must give priority to proposals which conform to these standards.  Futhermore, given the evidence now available about effect sizes there is no reason why future studies should not be adequately powered.  The theoretical basis of all interventions should be explicit, and reporting using CONSORT standards should be the norm (e.g. Hollis 2005).

Likely losses to follow-up for this age group must also be considered in the research design and the assumption that losses to follow-up are non-quitters (whilst representing the current "gold standard”) needs testing. Every effort should be made to keep the latter as small as possible, so that intention-to-treat analysis with missing subjects treated as continuing smokers can be carried out without excessive bias towards the null. Brown 2003 and Peterson 2009 demonstrate good practice in this respect. Subsidiary analysis of data with other imputed data is acceptable but should not represent the main result.

Biochemical verification remains the gold standard (West 2005).  If this is used, note should be made of comments on the limitations of exhaled CO given the episodic nature of smoking in this population.  However, although it is recognized that self reports in this cohort are not necessarily reliable, use of verification can affect recruitment and retention and a pragmatic decision needs to be taken in study design, balancing these factors.

Few of our studies complied with Russell Standards (Analysis 9.1). Six months follow-up should be a minimum requirement, and research now needs to move on to using outcomes based on sustained, continuous quitting in line with the Russell Standards (West 2005). Longer interventions, perhaps with relapse prevention as a feature, need to be further explored. As a complementary measure, long-term prospective studies of the natural smoking history of those making quit attempts in adolescence are needed. Finally, as the field matures, direct comparisons of effective treatments should become possible and should support full economic analyses.

Acknowledgements

We would like to thank Paul Aveyard and Cathy Backinger for reading and commenting on drafts of the initial review. Our gratitude goes to Review Group Co-ordinators and staff, who have been untiring in their support, especially with searches and with software applications, and to all the trialists who supplied additional data or information for this review. We would particularly like to thank Steve Sussman for sharing with us the bibliography of his systematic reviews. These have provided invaluable secondary checks of our search and quality assessment strategies. No additional studies were identified from these bibliographies as meeting the criteria for inclusion in this Cochrane Review.

Data and analyses

Download statistical data

Comparison 1. Effect sizes for all studies with extractable data
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Subgroups by abstinence definition27 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
1.1 Sustained or prolonged abstinence4 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.2 30 day point prevalence abstinence8 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.3 7 day point prevalence abstinence12 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.4 Other abstinence measure9 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
2 New studies in 20134 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
Analysis 1.1.

Comparison 1 Effect sizes for all studies with extractable data, Outcome 1 Subgroups by abstinence definition.

Analysis 1.2.

Comparison 1 Effect sizes for all studies with extractable data, Outcome 2 New studies in 2013.

Comparison 2. TTM vs standard care or dietary advice
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Cessation at 1 year31662Risk Ratio (M-H, Fixed, 95% CI)1.56 [1.21, 2.01]
2 Cessation at 2 years21537Risk Difference (M-H, Fixed, 95% CI)0.03 [-6.17, 0.06]
Analysis 2.1.

Comparison 2 TTM vs standard care or dietary advice, Outcome 1 Cessation at 1 year.

Analysis 2.2.

Comparison 2 TTM vs standard care or dietary advice, Outcome 2 Cessation at 2 years.

Comparison 3. Motivational enhancement vs brief interventions
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Cessation at 6 months or longer122667Risk Ratio (M-H, Fixed, 95% CI)1.60 [1.28, 2.01]
2 Complex interventions including Motivational Interviewing61583Risk Ratio (M-H, Fixed, 95% CI)1.88 [1.30, 2.72]
Analysis 3.1.

Comparison 3 Motivational enhancement vs brief interventions, Outcome 1 Cessation at 6 months or longer.

Analysis 3.2.

Comparison 3 Motivational enhancement vs brief interventions, Outcome 2 Complex interventions including Motivational Interviewing.

Comparison 4. Interventions including Cognitive Behavioural Techniques
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Cessation at 6 months or longer13 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
Analysis 4.1.

Comparison 4 Interventions including Cognitive Behavioural Techniques, Outcome 1 Cessation at 6 months or longer.

Comparison 5. Complex interventions using M I, Social cognitive theory, CBT or/and TTM
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Biochemically verified 6 month continuous abstinence2456Risk Ratio (M-H, Fixed, 95% CI)1.18 [0.80, 1.72]
2 6 month continuous cessation2836Risk Ratio (M-H, Fixed, 95% CI)1.72 [1.03, 2.86]
3 Cessation at 6 months, ≧ 7days PPA1402Risk Ratio (M-H, Fixed, 95% CI)1.10 [0.74, 1.62]
Analysis 5.1.

Comparison 5 Complex interventions using M I, Social cognitive theory, CBT or/and TTM, Outcome 1 Biochemically verified 6 month continuous abstinence.

Analysis 5.2.

Comparison 5 Complex interventions using M I, Social cognitive theory, CBT or/and TTM, Outcome 2 6 month continuous cessation.

Analysis 5.3.

Comparison 5 Complex interventions using M I, Social cognitive theory, CBT or/and TTM, Outcome 3 Cessation at 6 months, ≧ 7days PPA.

Comparison 6. NoT (Not on Tobacco)
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Cessation at 6 months or longer61420Risk Ratio (M-H, Fixed, 95% CI)1.31 [1.01, 1.71]
2 NoT+Fit vs Control1143Risk Ratio (M-H, Fixed, 95% CI)1.97 [1.02, 3.79]
3 NoT+Fit vs NOT1170Risk Ratio (M-H, Fixed, 95% CI)1.48 [0.88, 2.48]
Analysis 6.1.

Comparison 6 NoT (Not on Tobacco), Outcome 1 Cessation at 6 months or longer.

Analysis 6.2.

Comparison 6 NoT (Not on Tobacco), Outcome 2 NoT+Fit vs Control.

Analysis 6.3.

Comparison 6 NoT (Not on Tobacco), Outcome 3 NoT+Fit vs NOT.

Comparison 7. ICT-based interventions
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 30 day PPA at 6 months1139Risk Ratio (M-H, Fixed, 95% CI)0.44 [0.14, 1.36]
2 7 day PPA at 12 months2 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
3 30 day abstinence at 12m1448Risk Ratio (M-H, Fixed, 95% CI)1.80 [1.19, 2.71]
Analysis 7.1.

Comparison 7 ICT-based interventions, Outcome 1 30 day PPA at 6 months.

Analysis 7.2.

Comparison 7 ICT-based interventions, Outcome 2 7 day PPA at 12 months.

Analysis 7.3.

Comparison 7 ICT-based interventions, Outcome 3 30 day abstinence at 12m.

Comparison 8. Pharmacological interventions
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Point prevalence abstinence at six months3 Risk Ratio (M-H, Fixed, 95% CI)Totals not selected
1.1 Nicotine patch + bupropion versus nicotine patch + placebo1 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.2 Nicotine patch versus placebo1 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.3 Nicotine gum versus placebo1 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
1.4 Bupropion vs placebo1 Risk Ratio (M-H, Fixed, 95% CI)0.0 [0.0, 0.0]
Analysis 8.1.

Comparison 8 Pharmacological interventions, Outcome 1 Point prevalence abstinence at six months.

Comparison 9. Russell Standards
Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size
1 Biochemically verified 6 month continuous abstinence2456Risk Ratio (M-H, Fixed, 95% CI)1.18 [0.80, 1.72]
Analysis 9.1.

Comparison 9 Russell Standards, Outcome 1 Biochemically verified 6 month continuous abstinence.

What's new

Last assessed as up-to-date: 31 July 2013.

DateEventDescription
24 June 2013New search has been performedSearches updated in February 2013. 4 new studies included and risk of bias tables expanded.
6 June 2013New citation required but conclusions have not changedChange in author order. No major changes to conclusions.

History

Protocol first published: Issue 3, 2005
Review first published: Issue 4, 2006

DateEventDescription
6 November 2009New search has been performedUpdated for issue 1, 2010. Eight new studies included, no major change to conclusions
30 October 2009New search has been performedConverted to new review format.

Contributions of authors

Both authors conceived the review, and both selected and extracted data. GG and AS wrote the review in collaboration.

Declarations of interest

None known.

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Aveyard 2001

MethodsCountry: UK
Setting: Schools in West Midlands
Study design: Cluster randomized controlled trial. Schools sampled with probability in proportion of size of year group. Combined prevention/cessation trial
ParticipantsParticipants: 1089 adolescent smokers (defined as >=1 cpw) (I 547; C 542)
Age range: 13-14 yrs
Criteria for inclusion: Inclusion was at level of school; 89 schools approached, 53 agreed to participate. Data extracted for this cessation review based on all pupils in year 9 who smoked >=1 cpw
Follow-up method: Questionnaire to all students
Inducements to enter study: None
Pre-study Smoking status assessment: self reported
Post study smoking status assessment: self reported
Significant demographic differences between arms of trial: None apparent in published data*
InterventionsIntervention: Computer 'expert system' designed to diagnose stage of change and deliver material tailored to individual. Six sessions, 2 per term, 1 class-based (tutor training mandatory) and one computer-based delivered over period of school year (3 school terms per year in UK).
Theoretical basis of intervention: Psycho-social intervention based on transtheoretical model of stages of change.
Control: Control schools received health education as delivered locally at that time; in addition teachers received 3 lesson plans plus handouts but no specialist training or record of what was delivered.
Theoretical basis of control: Normal local practice
OutcomesMeasurement: 7-day and 30-day PPA (supplied by author); Follow-up periods >3m, 12m (mean length of follow-up 359 (I) to 347 (C) days) and 24m from start of study, equivalent to 4m and 16m after end of intervention.
Verification: None
Losses to follow-up: 11% (I) and 10.7% (C) @ 12m; 14% (I) and 16.9% (C) @ 24m (additional data from authors).
Notes7- and 30-day abstinence at 12 & 24m provided by author based on pupil reporting as quitting AND abstinent for stated period as opposed to not smoking for stated period. The latter is basis for results given in this review.
Tested sensitivity of questionnaire kappa 0.87 (0.7-1.00) bias would be towards positive result so ascertainment unlikely to affect validity
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputer-generated block randomization, balanced by class size
Allocation concealment (selection bias)Low riskComputerised and anonymous
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskNo biochemical validation, but follow-up surveys anonymised (identified only by ID number) and delivered by trained personnel in 'examination' setting, differential misreport judged to be unlikely
Incomplete outcome data (attrition bias)
All outcomes
Low riskAnalyses tested all models of losses to follow-up
Other biasUnclear riskFidelity of implementation for controls unclear

Brown 2003

MethodsCountry: USA
Setting: Psychiatric hospital, Providence RI
Study design: Randomized controlled trial
ParticipantsParticipants: 191 patients (I 116 ; C 75), 62.3% female, ethnicity 94.8% white
Age range: 13-17 year olds, mean 15.4 yrs
Criteria for inclusion: at least 1 cpw for previous 4 weeks, 64% daily smokers, on average smoking for 3.6 years (additional data from authors)
Follow-up method: Telephone questionnaire
Inducements to enter study: Gift certificates to local mall, escalating in value, on completion of each phase
No significant demographic differences between arms of trial.
Other: Participants were prohibited from smoking during hospital stay (mean length 9 days)
InterventionsIntervention: Motivational interviewing given in 2 sessions of 45 mins plus relapse prevention manual and self help pamphlet
Control: Brief advice session plus self-help pamphlet
OutcomesMeasurement: 7-day PPA; follow-up period/s >3m, 6m, 12m
Pre-study smoking status assessment: Modified Fagerstrom, mean 4.9 (±1.82)
Post study smoking status assessment.
Verification: Salivary cotinine and CO
Losses to follow-up: At 6m 8%; at 12m 9%
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"The assignment of cohorts to treatment condition was determined randomly before the initiation of the study," method of sequence generation not specified
Allocation concealment (selection bias)High riskAllocation based on time of admission. "Between cohorts, no recruitment occurred until study participants from the previous cohort had been discharged from the hospital."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified, not clear if other hospital personnel blind to treatment assignment
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used at 1, 6 and 12m follow-up visits
Incomplete outcome data (attrition bias)
All outcomes
Low risk91% followed up at 12 months, "rates of missing data were not significantly different across motivational intervention and brief advice conditions."

Chan 1988

MethodsCountry: USA
Setting: University dormitories, Richmond VA
Study design: Cluster controlled trial; Only two arms contribute (Health Risk Assessment with and without feedback) as single control group not measured at beginning and end of study.
ParticipantsParticipants: 40 University freshmen smokers
Age range: 17-18
Criteria for inclusion: 50% of freshman randomly selected.
Follow-up method: Computer scored Health Risk Appraisal [HRA] Questionnaire
Inducements to enter study: None
Pre-study Smoking status assessment: self assessment
Post study smoking status assessment: self assessment verified by resident advisor with option to modify
No significant demographic differences between arms of trial.
InterventionsFour-arm trial:
1) Health Risk assessment [HRA] at start of study, feedback on results and second assessment 1 year later (n=23)
2) HRA at start of study and HRA at end (n=17)
3) HRA at start only (no end of study data collection on smoking behaviour)
4) HRA at end only (no baseline data collection on smoking behaviour)
Only arms (1) and (2) compared for this review
OutcomesMeasurement: self-reported 30-day PPA; Follow-up period/s >3m; approx 9m.
Verification: resident advisor's report, with no biochemical validation
NotesAs data collection on control groups was not done before and after, only one comparison can be made. Authors noted that there was a risk of contamination between groups.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskFour dormitories assigned to four conditions, method of assignment not specified
Allocation concealment (selection bias)High riskAssignment based on dormitory, allocation concealment not specified
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskNo biochemical validation used but verification obtained through resident advisor's report, "who interacted with the freshman on a daily basis," differential misreport unlikely.
Incomplete outcome data (attrition bias)
All outcomes
Low risk6 students who withdrew from university excluded from final denominator, 100% follow-up for all others
Other biasUnclear riskContamination possible: "...informational exchange among students in different groups might still occur."

Colby 2005

MethodsCountry: USA
Setting: Hospital outpatient or emergency departments in Rhode Island
Study design: Randomized controlled trial
ParticipantsParticipants: 85 adolescents (43 I; 42 C)
Age range: 14 -19 yrs
Criteria for inclusion: reported daily smoking for previous 30 days
Follow-up method: Timeline Follow Back to inform structured interview
Inducements to enter study: US$10 gift voucher for completion.
Pre-study Smoking status assessment: self reported cpd in last 30 days
Post study smoking status assessment: verified self-reported smoking pattern in last 90 days
Significant demographic differences between arms of trial: Not reported
InterventionsIntervention: 35 minute personal motivational interview with 1 week follow-up phone call of 15- 20 minutes
Theoretical basis of intervention: Motivational enhancement
Control: 5 minute advice interview plus pamphlet and brief phone call 1 week after visit
Theoretical basis of control:Brief Intervention
OutcomesMeasurement: 7-day PPA; follow-up periods: >3m, 6m.
Verification: CO and cotinine
Losses to follow-up: 20% at 6 months
NotesAuthor of study considers little confounding amongst extensive array of variables
High withdrawal and non-recruitment rate.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly assigned," method of sequence generation not specified
Allocation concealment (selection bias)Unclear riskNot specified
Blinding of participants and personnel (performance bias)
All outcomes
Unclear risk"The research assistants in this study were blind to treatment condition," unclear if participants in control group knew of intervention being provided.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
Low riskParticipants lost to follow-up counted as smokers, 80% of participants followed up at 6m, no significant difference in loss to follow-up between treatment groups

Greenberg 1978

MethodsCountry: USA
Setting: High schools
Study design: Randomized controlled trial
ParticipantsParticipants: Open recruitment, first 100 recruited
Age range: 14 -16 (Grades 9-11 )
Criteria for inclusion: All participants smoked at least 5 cpd
Inducements to enter study: Half a unit credit for experimental groups
Pre-study Smoking status assessment: self report
Post study smoking status assessment: self report
InterventionsIntervention: Group A (n=25) received 'scare' education; Group B (n=25) 'fact'-based education, Group C (n=25) 'attitude' approach using affective strategies. All classes took place in weekly sessions over 7 weeks.
Theoretical basis of intervention: Affective teaching strategies consistent with theoretical development at time of trial
Control: Control group (n=25) spent time in study hall without any active intervention
OutcomesMeasurement: PPA ['no longer smoked']; follow-up period/s >3m, 5m after end of intervention. Intervention lasted 7 weeks, so endpoint 6-7m post-baseline.
No biochemical verification.
Losses to follow-up: 22% at final follow-up.
Results:
All ORs calculated. Quitters: Group A 3 students; Group B 0 students; Group C 6 students and control 1 student
Overall OR for aggregated quitting = 3.27 (0.39 - 27.21)
Group A vs control OR = 3.27 (0.32-33.84)
Group B vs control OR = 1(0)
Group C vs control OR = 7.58 (0.84 - 68.46) (displayed in analyses
NotesNo power calculations evident from paper but published in 1978 so report consistent with current practice.
Lack of information regarding allocation and potential confounding in this study.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskNot specified, not clear if randomization used
Allocation concealment (selection bias)High risk"The subjects were divided into four equal groups... designated to meet during four different daily class periods," suggests allocation was not concealed
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
High risk"An attempt was made to validate the self-report data by asking about smoking behaviour in two different parts of the questionnaire by two differently-worded questions." Self-reported smoking status used, differential misreport possible.
Incomplete outcome data (attrition bias)
All outcomes
Low risk78% followed up at 5m, rates similar in each group

Hoffman 2008

MethodsCountry: USA
Setting: 7 Public high schools in Montgomery county, Maryland
Study design: Cluster randomized controlled trial randomized at level of school
ParticipantsParticipants: 105 adolescent smokers
Age range: 14 - 18
Criteria for inclusion of school: Not currently participating in any other smoking cessation interventions
Criteria for inclusion of students: Those who had smoked ≥1 cpd for 30 days and were willing to attend 6 sessions plus follow-up at 1 year.
Follow-up method: Project team interviews face-to- face and by telephone
Inducements to enter study: None
Pre-study Smoking status assessment: self-reported 30-day smoking status
No significant demographic differences in participants in arms of study
InterventionsIntervention: ASCENT programme included "cognitive behavioural therapy" tailored to stage of change (TTM), a student workbook, role play, discussion and games and video all delivered over 6 sessions of 1 hour per week over 6 weeks. However, as intervention was delivered to a group, TTM component not strictly applied.
Theoretical basis of intervention: TTM and CBT
Control: Normal teaching and information giving within school
OutcomesMeasurement: Quitting defined as no smoking in 24 hrs prior to interview.
Follow-up periods: 3m, 1 year.
Verification: Saliva cotinine attempted but either kits failed or students didn't provide sample.
Losses to follow-up: 16% at 12 months
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Schools were randomized," method of sequence generation not specified
Allocation concealment (selection bias)Low riskSchools randomized, not participants. Students recruited prior to status of school being known.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
High riskCotinine collected but not used, previous studies have found high misreport in adolescents even when aware biochemical validation would be used, hence misreport cannot be ruled out for this study
Incomplete outcome data (attrition bias)
All outcomes
Low risk16% loss to follow-up at 12m, "A series of attrition analyses examining both the 30-day and 12-month follow-up data indicated no differential loss of youth by condition, sex, racial group or having plans to quit in the next 30 days."

Hollis 2005

MethodsCountry: USA
Setting: 7 pediatrics and family practice departments in HMO medical centres in Oregon and Washington state.
Study design: Randomized controlled trial (prevention and cessation). Blocked randomization method, using sealed envelopes.
ParticipantsParticipants: 448 adolescent smokers selected from 2524 recruits attending clinic appointments.
Age range: 14 - 17
Criteria for inclusion: Those who were willing to stay after consultation at clinic and had no intention of leaving geographical area within 1 year.
Follow-up method: Mailed questionnaires and telephone interviews
Inducements to enter study: None
Pre-study Smoking status assessment: self-reported 30-day smoking status
Non-significant demographic differences between arms of trial at level of P < 0.05 except for small difference in positive at depression screen (P < 0.01)
InterventionsIntervention: 3 sequential interventions plus maximum of 2 boosters:
(1) Clinical message encouraging quitting or not starting, (2) 10-12 minute individual multi-media interactive computer-delivered expert system tailored to stage of change of individual (3) 3-5 mins of motivational counselling by trained health counsellors. Boosters were delivered at clinic attendance (computer programme and motivation counselling) or by telephone (motivational counselling only). Repeated attempts were made to deliver boosters.
Theoretical basis of intervention: Prompts to clinicians to give brief advice, TTM and motivational interviewing
Control: Dietary advice (5-a-day fruit and vegetables); Theoretical basis of intervention: Brief advice - 3-5 mins motivational counselling
OutcomesMeasurement: 30-day PPA; Follow-up periods: >3m, 1 year and 2 years.
No verification.
Losses to follow-up: 6% at 12 months and 12% at 24 months
NotesThis systematic review uses definition of smoking of 1 cpw for at least 6m to define a regular smoker. Hollis et al confirm that their definition of 'smokers' most closely fits this criterion.
We have only used the data for smokers, although the trial included separate smoking uptake prevention results.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"blocked over time and stratified according to medical centre and 30-day cigarette smoking status," method of sequence generation not specified
Allocation concealment (selection bias)Low risk"Study staff members not involved in recruitment or randomization printed the stratified allocation assignments on index cards and concealed the cards in envelopes."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
High riskAssessor blinded, but no biochemical validation used. Differential misreport possible.
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up at 2y higher in treatment group (14.3%) than in control group (10.1%). Six types of analyses to model missing data, including ITT analysis in which participants lost to follow-up counted as smokers. "Conclusions were largely consistent among the various missing-data procedures."

Horn 2007

MethodsCountry: USA
Setting: Suburban Emergency Department
Study design: Randomized controlled trial
ParticipantsParticipants: Presenting for care at an ED (excluding those not competent or in police custody) 40/75 in Intervention and 35/75 in control arm
Age range:14-17
Criteria for inclusion: Reported smoking within 30 days, willing to participate and providing written consent
Follow-up method: Phone calls
Inducements to enter study: None
Pre-study Smoking status assessment: mFTQ and CO
InterventionsIntervention: 5 stage Motivational Interviewing (1) screening (2) Tailored interview of 15-30 mins (3) stage sensitive homework book (4) handwritten postcard within 3 days (5) Motivational phone calls at 1/12, 3/12 and 6/12.
Theoretical basis of intervention: Motivational Interviewing
Control: Brief intervention including screening, generic advice giving (2 mins) referral to information line
Theoretical basis of control: Normal care
OutcomesMeasurement: Self report at 6 months. 1 person quit in both intervention and control.
Verification. None
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputerized: "sequentially numbered...as sorted by the SAS random number function"
Allocation concealment (selection bias)Low riskAllocation concealed in manila study envelope, single pile, sequentially numbered. "Each randomized manila folder contained either the MTI or the BA protocol set of equal size and weight."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear risk"Each provider was blinded during the initial screening." No further blinding reported.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskNo biochemical validation used, different levels of intensity between groups, differential misreport possible, however, only 1 participant in each group reported abstinence so outcome unlikely to have been affected by detection bias.
Incomplete outcome data (attrition bias)
All outcomes
High risk60% intervention and 65% control lost to follow-up at 6m. Authors state: "follow-up found low retention rates, presenting potential biases in our data" though "no significant differences between absent and present teenagers at 6-month follow-up were observed."

Joffe 2009

MethodsCountry: Maryland, USA
Setting: 4 High schools (I: 2; C:2)
Study design: Randomized controlled trial with individuals randomised within schools, schools allocated in balanced blocks
Participants

Participants: 193 students (I: 104; C: 104).
Age range: 14-18 years, mean 15.9
Criteria for inclusion: self-report of smoking AND expressed willingness to quit
Follow-up method: Self reports and salivary cotinine verification of smoking status

Inducements to enter study: Sessions conducted over lunch which was provided plus "modest incentives"

Verification of smoking status: None

Pre study smoking status assessment: self reports, age first smoked and "nicotine dependence".
Significant demographic differences between arms of the trial: slight imbalance in ethnicity, age, nicotine dependence and quit attempts

Post study smoking status assessment: Self report and salivary cotinine

InterventionsIntervention: "Kickin' Butts": 15 lunch time sessions of 25/30 mins (compared to 8 x 50 mins sessions of original intervention)
Theoretical basis of intervention: Programme used that of Adelman 2000 (see Excluded studies for references). Programme design "guided by information gathered in preliminary focus groups, directed interviews, and current teen and adult smoking cessation programs."
Control: Brief Intervention of one session with pamphlets
OutcomesMeasurement: 30 day point prevalence abstinence
Follow-up periods: 6 months and 12 months
Verification: Self reporting verified by salivary cotinine
Losses to follow-up: 69% followed up at 6 months and 62% at 12 months
Notes

New for 2013.

Same study also evaluated a NoT intervention, see NoT MD 2009

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskBlock randomization, no information given on sequence generation
Allocation concealment (selection bias)Unclear riskNot specified
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNo blinding of personnel, not clear if participants knew what intervention other group was receiving
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
Low riskNo significant difference between groups in terms of percentage lost to follow-up. Authors conducted two ITT analyses, one treating those lost to follow-up as smokers.

Kelly 2006

MethodsCountry: Australia
Setting: Three state high schools in Brisbane
Study design: Randomized controlled trial. Students referred into trial as a result of violation of smoking policy.
ParticipantsParticipants: 56 students (34% female)
Age range: 14-16 years with parental consent
Criterion for Inclusion: Violation of school smoking policy
Pre study status assessment: Modified Fagerstrom 3.6±1.4, consumption ∼50 cpw
follow-up method: 1,3 and 6 month self-reported tobacco use
Inducements: Not stated
Pre-study smoking status assessment: self reporting
InterventionsIntervention: Motivational Interview with trained interviewer of 1 hour duration with information targeted directly at reported experiences of smoking additional reading following interview
Control: Standard care interview of 1 hour duration and within interview use of a "quit kit" plus review of general literature on effects of smoking within interview time.
OutcomesMeasurement: 30 day PPA no verification
follow-up periods 3/12 and 6/12
Losses to follow-up: 25% at 6 months assumed relapsed.
NotesModerate differences in intervention and control groups but not regarded as significant to outcomes of study
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly assigned," no further information provided
Allocation concealment (selection bias)Unclear riskNot specified
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified, not clear if participants knew what interventions the other group was receiving
Blinding of outcome assessment (detection bias)
All outcomes
High riskNo biochemical validation used, interventions delivered by author, differential misreport possible
Incomplete outcome data (attrition bias)
All outcomes
Low riskSimilar loss to follow-up in both groups (6/30 intervention, 8/26 control), participants lost to follow-up counted as smokers in ITT analysis. "To test for attrition bias, differences between attritors and nonattritors were tested using one-way ANOVAs... There were no significant differences on any variables except mother's occupational status."

Killen 2004

MethodsCountry: USA
Setting: Nine continuation high schools in San Francisco, CA
Study design: Randomized controlled trial. Quality of allocation concealment confirmed by author.
ParticipantsParticipants: 211 smokers.
Age range: 15-18 years
Criteria for inclusion: currently smoked at least 10 cpd, for at least 6m, with >1 quit attempt and a score of at least 10 on modified FNTQ.
Inducements to enter study: US$50 at end of treatment and US$50 for completing 6m assessment.
Pre-study Smoking status assessment: mean cpd 15 and mean FNTQ score 16.6
No significant demographic differences between arms of trial.
Health screening was conducted; those screened positive for depression (clinical diagnosis) were excluded
InterventionsIntervention: 8 weeks of tailored NRT patch therapy plus 150mg SR bupropion tablet (for 8 weeks from quit date) and relapse prevention
Theoretical basis of intervention: Pharmacological plus group work (theoretical basis not given)
Control: 8 weeks of tailored NRT patch therapy plus placebo tablet. (for 8 weeks from quit date)
OutcomesMeasurement: 7-day PPA; follow-up periods: >3m, 6m.
Verification: CO monitoring (below 9ppm) and saliva cotinine (below 20 ng/ml) at 6m; adherence to bupropion measured at 5 weeks
Losses to follow-up: 36% at 6m.
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomization method not described.
Allocation concealment (selection bias)Unclear risk"Assignment to treatment condition was double blind," no further information provided.
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"Double blind," no further information provided, but placebo used and treatment effect not found, performance bias judged to be unlikely
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemically validated abstinence
Incomplete outcome data (attrition bias)
All outcomes
Low risk38% bupropion & 35% placebo lost at 6 months, included in analysis.

Lipkus 2004

MethodsCountry: USA
Setting: 11 shopping malls and an amusement park in North Carolina, South Carolina, Gerogia and Tennessee
Study design: Randomized controlled trial
ParticipantsParticipants: 402 adolescents (I 209; C 193)
Age range: 15-18 years old
Criteria for inclusion: ≥1 cigarette within preceding 7 days (mean years smoked 3 ±2, and 10 ±8 cpd)
follow-up: Telephone survey
Inducements to enter study: a movie pass
Pre-study smoking status assessment: Nicotine dependence measured using mFTQ
No significant demographic differences between arms of trial.
InterventionsIntervention: Telephone counselling, self help materials and a video
Theoretical basis of intervention: Eclectic but pre-tested with age-appropriate group and contains elements of CBT and TTM. Telephone counselling used motivational interviewing
Control: Self help materials and a video
Theoretical basis of control: Eclectic, see above
OutcomesMeasurement: 7-day PPA and sustained abstinence (defined as not smoking at both 4m and 8m assessment points); follow-up periods >3m, 8m.
Verification: saliva cotinine at level of >10ng/ml at 4m; self-report only at 8m.
Losses to follow-up: 36% at 8m.
Results: 7 day quitting: 21% (calculated as 44 smokers ) in intervention and 19% (calculated as 37) in control. Sustained quitting 9% (calculated as 19) in intervention arm and 7% (calculated as 14) in control.
ITT for sustained quitting OR =1.279 (0.622 - 2.627)
ITT for 7 day point prevalence OR = 1.124 (0.690 - 1.833)
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomized, method not described, stratified by SoC
Allocation concealment (selection bias)Unclear riskNo details given
Blinding of participants and personnel (performance bias)
All outcomes
Low riskDue to minimal contact nature of intervention, performance bias unlikely
Blinding of outcome assessment (detection bias)
All outcomes
High riskBiochemical validation done but final outcome figures based on self-report only. High failure to confirm and low response rate.
Incomplete outcome data (attrition bias)
All outcomes
Low risk46% Int & 51% Cont reached at both follow-ups. Losses included as smokers.

Moolchan 2005

MethodsCountry: USA
Setting: Baltimore, MD, by invitation through media advertisements, schools, churches.
Study design: Randomized controlled trial
ParticipantsParticipants: 120 Smokers (I 80, C 40)
Age range: 13-7 years
Criteria for inclusion: Smoking 10 or more cpd for at least 6m and motivation to quit >5 on 10-point integer scale. Only those who were happy to inform parents of smoking status were included.
Follow-up method: interim and final questionnaires and final visit for verification of smoking status
Inducements to enter study: US$90 for baseline and US$135 after final visit/completion
Pre study Status assessment: Mean 18.8 cpd, 'youth appropriate' Fagerstrom mean 7.04
No significant demographic differences between arms of the trial.
InterventionsIntervention: Nicotine patch and gum, and self-help written materials. Two active groups (a) active patch with placebo gum (n=34) (b) active gum with placebo patch (n=46). NRT for both groups was tailored to weight and smoking level. Participants received 11 visits over 12 weeks to receive NRT, and attended 45 minute group CBT session at the end of each visit, + self-help materials. Theoretical basis of intervention: Pharmacological
Control: placebo patch and gum (n=40).
OutcomesMeasurement: 7-day PPA, and 'prolonged' abstinence, i.e. continuous abstinence after a 2 week grace period from end of intervention; Follow-up periods: >3m, 6m.
Verification: CO, salivary cotinine and thiocyanate.
Losses to follow-up: 54%
NotesTimeline for trial was verified with authors.
Adverse event 'profile consistent with that reported for adults'.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Randomized ... according to an algorithm held by the National Institute on Drug Abuse Pharmacy, with true replacement of the non-completers".
Allocation concealment (selection bias)Unclear riskNot stated
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskDescribed as "double-blind, double-dummy", but no further information.
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemically validated abstinence
Incomplete outcome data (attrition bias)
All outcomes
Low riskLosses to follow-up were included as failures for cessation. Losses fully reported.

Muramoto 2007

MethodsCountry: Arizona, USA
Setting: Community recruitment
Study design: Double-blind randomized controlled trial with two treatment arms.
ParticipantsParticipants: 312 smokers (I 209; C 103)
Age range:14 -17 years
Criteria for inclusion: Smoking at least 6 cpd & exhaled CO≧10ppm & at least two prior quit attempts & no major psychiatric diagnosis
Follow-up method: Telephone visit at 12 weeks and 26 weeks post target quit date.
Inducements to enter study: None
Pre-study smoking status assessment: Self report previous 90 days, mFTQ and CO verification
InterventionsIntervention 1: Buproprion SR 300 mg/day in blister cards
Intervention 2: Buproprion SR 150 mg/day in blister cards
Theoretical basis of intervention: Pharmacological Phase III trail including "standardised brief individualised counselling" at each visit.
Control: 0 mg/day placebo tablet identical to active tablets and blister packed
Theoretical basis of control: Pharmaceutical
OutcomesMeasurement: Self reports of 7 day point prevalence (30 day PPA stated as an outcome in paper but figures not given, not obtainable from author) at 26 weeks
Verification: Exhaled CO at 26 week visit
Notes300 mg versus placebo displayed in analyses. 150 mg had fewer quitters than control (2/105, vs 6/103, RR 0.33 95% CI 0.07, 1.58). Losses to follow-up: 19/104 in 300 mg, 31/105 in150 mg, 19/105 in control
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk"Active study medication and identical-appearing placebo were prepackaged into 3 sets of identical-appearing blister cards in accordance with a computer-generated randomization list."
Allocation concealment (selection bias)Low risk"... a research assistant assigned the subject the next treatment number (and associated blister cards) in sequence."
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"Study subjects and researchers remained blind to treatment group assignment throughout the study," identical appearing placebo used (see above)
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBlinded and biochemically validated abstinence
Incomplete outcome data (attrition bias)
All outcomes
Low riskSlightly higher lost to follow-up/ declined further participation in placebo group (30%) than active arms (18%). ITT analysis.

Myers 2005

MethodsCountry: USA
Setting: Outpatients in substance abuse programme in Southern California
Study design: Non-randomized controlled trial
ParticipantsParticipants: 54 Smokers: (I 26; C 28 [on waiting list])
Age range: 13-18 years, mean 16.1 yrs
Criteria for inclusion: Reported weekly smoking, smokers were required to attend treatment but participation in the outcome study was voluntary
Follow-up method: questionnaires and visit for verification of smoking status/
Inducements to enter study: Gift certificates US5 for baseline, US5 for 3m follow-up and US$45 on completion at 6m.
Pre study Status assessment: Mean 7.96 cpd in intervention group and 10.0 in control group, modified Fagerstrom scores of 3.85 in intervention group and 3.68 in control group
Post study smoking status assessment: Teen Smoking Questionnaire
Significant demographic differences between arms of the trial: Authors claim statistically significant difference only in % of pre-contemplators, although we note that the control group had fewer girls than the intervention group (14% vs 31%).
InterventionsIntervention: Motivational enhancement delivered in 6 sessions of 1 hour each in groups.
Theoretical basis of intervention: Eclectic with CBT and motivational enhancement
Control: waiting list
OutcomesMeasurement: 7-day and 90-day PPA and Time Line follow back; Follow-up periods: >3m, 6m.
Verification: CO and salivary cotinine, and parental corroboration
Losses to follow-up: 33%
NotesAdditional information from author
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High risk"We used a sequential cohort design whereby conditions were successively switched between SRC (intervention) and WL (waiting list) within each site."
Allocation concealment (selection bias)High riskSee above
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNo information provided, unclear if waiting list participants knew they were being placed on hold to receive treatment
Blinding of outcome assessment (detection bias)
All outcomes
Low riskAbstinence biochemically validated
Incomplete outcome data (attrition bias)
All outcomes
Low risk67% completed 6m follow-up. "Attrition analyses... indicated no significant differences on demographic or baseline smoking variables between missing and included participants at any
follow-up assessment time point. Chi-square analyses indicated no differential attrition by treatment condition at any time point."

NoT AL 2008

MethodsCountry: Alabama, USA
Setting: 71 High schools (I: 44; C: 27)
Study design: Randomized controlled trial
ParticipantsParticipants: 400 students (I 192; C 208).
Age range: 16-18 years (subset),
Criteria for inclusion: Willingness to consent and self-report of smoking
Follow-up method: Self reports and verification of smoking status
Inducements to enter study: Originally participants given small value key chains. Later stages of study incentives changed to $5-$20 rising as increasing time from baseline
Verification of smoking status: Salivary cotinine
Pre study smoking status assessment:
Significant demographic differences between arms of the trial: Intervention group had slightly higher nicotine dependence
Post study smoking status assessment:
InterventionsIntervention: NoT Intervention: 1 x 50-minute session once a week for 10 weeks, same-gender small groups (no more 10 in the group) led by same-gender facilitators. Covers motivation, smoking history, nicotine dependence, social, psychological and health consequences of smoking, preparation for quitting, urges and cravings, relapse prevention, stress management, family/peer pressure, healthy lifestyle, nutrition. Four booster sessions offered post-programme at 2 and 4 weeks.
Theoretical basis of intervention: Social cognitive theory
Control: Brief Intervention (mixed gender groups, 5 minutes scripted advice, 10 minutes to describe purpose and answer questions, pamphlets)
OutcomesMeasurement: 7 day & 30 day PPA
Follow-up periods: 6 months and 12 months
Verification: Self reporting with a sub-group verified by salivary cotinine.
Losses to follow-up: 63% at 6 months and 71% at 12 months. Losses to follow-up much higher in Intervention group - 77% vs 49% at 12 months
NotesThe original study included 16-19 year olds. This review uses 7 day PPA data for 16-18 year olds supplied by Investigators. Losses to follow-up given are for 16-19 year old group. Demographic and motivational differences for participants. More difficulty reported in recruiting schools to Intervention Group.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskNot randomized, pre-post assessment design with comparison.
Allocation concealment (selection bias)High riskDifferent recruitment procedures for intervention and control groups. "Intervention schools were recruited... according to NoT procedures, including endorsement and support of high school administrators, faculty, and staff."
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
High riskDifferential and high losses to follow-up (at 12m, 21% intervention and 34% control available for follow-up).

NoT FL 2001

MethodsCountry: USA
Setting: 40 high schools in Florida
Study design: Cluster controlled trial. A matching procedure was used 'to better accommodate the community based research partners and challenges they faced (e.g. local schools who already had NoT in place )'.
ParticipantsParticipants: 423 Smokers in 40 schools (I 249; C 174)
Age range: 14-19 years,mean approx 16 years.
Criteria for inclusion: self-reported smoking at least 5cpd.
Follow-up method: self reports and verification of smoking status
Pre study smoking status assessment: Approx 11.7 cpd on weekdays and 18.2 cpd on weekends. mFTQ of around 6.0 (reported for each arm of trial)
Significant demographic differences between arms of the trial: Interevention group had slightly higher nicotine dependence.
InterventionsIntervention: NoT Intervention: 1 x 50-minute session once a week for 10 weeks, same-gender small groups (no more 10 in the group) led by same-gender facilitators. Covers motivation, smoking history, nicotine dependence, social, psychological and health consequences of smoking, preparation for quitting, urges and cravings, relapse prevention, stress management, family/peer pressure, healthy lifestyle, nutrition. Four booster sessions offered post-programme at 2 and 4 weeks.
Theoretical basis of intervention: Social cognitive theory
Control: Brief Intervention (mixed gender groups, 5 minutes scripted advice, 10 minutes to describe purpose and answer questions, pamphlets)
OutcomesMeasurement: 1-day or longer PPA; Follow-up periods: >3m, 6m (mean 7.3m from baseline)
Verification: CO
Losses to follow-up: approx 50%
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskNot randomized, researchers select schools from waiting list. "The study used a "matched" design. Each year, 10 NoT schools were selected and then a BI school was matched to each NoT school..."
Allocation concealment (selection bias)High riskSee above
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
High riskLarge and differential rate lost to follow-up: 42% control, 59% intervention.

NoT MD 2009

MethodsCountry: Maryland, USA
Setting: 4 High schools (I:2 and C:2)
Study design: Randomized controlled trial with individuals randomised within schools, schools allocated in balanced blocks
Participants

Participants: 194 students (I: 92; C: 102)
Age range: 14-18 years, mean 15.9
Criteria for inclusion: self-report of smoking AND expressed willingness to quit
Follow-up method: self report & salivary cotinine verification

Inducements to enter study: Sessions conducted over lunch which was provided plus "modest incentives"

Verification of smoking status: None

Pre study smoking status assessment: self reports, age first smoked and "nicotine dependence".
Significant demographic differences between arms of the trial: slight imbalance in ethnicity, age, nicotine dependence and quit attempts

Post study smoking status assessment: Self report and salivary cotinine

InterventionsIntervention: Modified NoT Intervention: 20 lunch time sessions of 25/30 mins (compared to 5 x 50 mins sessions of other NoT trials)
Theoretical basis of intervention: Social cognitive theory
Control: Brief Intervention of one session with pamphlets
OutcomesMeasurement: 30 day point prevalence abstinence measured
Follow-up periods: 6 months and 12 months
Verification: Self reporting verified by salivary cotinine
Losses to follow-up: at 6 months and at 12 months
Notes

New for 2013. Clarification of data and details of incentives sought from authors but not received at time of publication.

Same study also evaluated an alternative intervention, see Joffe 2009.

Modified NoT: entered as NoT since basis of intervention same but timescale of delivery modified.

Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risksee Joffe 2009
Allocation concealment (selection bias)Unclear risksee Joffe 2009
Blinding of participants and personnel (performance bias)
All outcomes
Unclear risksee Joffe 2009
Blinding of outcome assessment (detection bias)
All outcomes
Low risksee Joffe 2009
Incomplete outcome data (attrition bias)
All outcomes
Low risksee Joffe 2009

NoT NC 2002

MethodsCountry: USA
Setting: 10 high schools (5 matched pairs) in North Carolina
Study design: Cluster controlled trial. Intervention schools were allocated where there were NoT facilitators trained to deliver the intervention already present in the school.
ParticipantsParticipants: 122 smokers (I 61; C 61)
Age range: 14-19 years, mean approx 16 years. 93.4% white, 56% female.
Criteria for inclusion: self-reported smoking at least 5cpd.
Follow-up method: self reports and verification of smoking status.
Pre study smoking status assessment: Approx 13.3 cpd on weekdays and 19.4 cpd on weekends. Modified Fagerstrom score showed them 'highly addicted'
InterventionsNoT intervention with Brief Intervention as control. See NoT Florida for details.
OutcomesMeasurement: 1-day or longer PPA; Follow-up periods: >3m, 6m, 15m.
Verification: CO < 9 ppm.
Losses to follow-up: approx 50% at 15m.
NotesITT data used.
End of programme, if including booster sessions, is around 6m. OR calculated from trial report.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskMatched but not randomized
Allocation concealment (selection bias)High riskNot randomized. Authors state, "Notably, the matching procedure does not account for possible confounders that might occur because the NoT schools chose to participate rather than being
randomly assigned to either a treatment or comparison group." Serious flaw and risk of confounding by picking intervention schools where already 'trained to administer' intervention in past (acknowledged).
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used at 3 and 6m follow-ups, "across the 3-month and 6-month observations, there was high agreement between self-report and carbon monoxide-validated quit rates"
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskNumber lost to follow-up not reported (report aggregates attrition from multiple studies). Overall, authors report "There were no significant differences in the attrition rate for NoT (22.5% absent) and BI (18.5% absent) groups, leaving an overall follow-up rate of approximately 80%."

NoT WV 2004

MethodsCountry: USA
Setting: 10 high schools (5 matched pairs) in North Carolina
Study design: Cluster controlled trial. Intervention schools were allocated where there were NoT facilitators trained to deliver the intervention already present in the school.
ParticipantsParticipants: 136 smokers (I 63; C 73)
Age range: 14-19 years, mean approx 16 years. 93.4% white, 56% female.
Criteria for inclusion: self-reported smoking at least 5cpd.
Follow-up method: self reports and verification of smoking status.
Pre study smoking status assessment: Approx 13.3 cpd on weekdays and 19.4 cpd on weekends. Modified Fagerstrom score showed them 'highly addicted'
InterventionsNoT intervention with Brief Intervention as control. See NoT Florida for details.
OutcomesMeasurement: 1-day or longer PPA; Follow-up periods: >3m, 6m, 15m.
Verification: CO < 9 ppm.
Losses to follow-up: approx 52% at 15m.
Notes 
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High riskMatched, not randomized
Allocation concealment (selection bias)High riskNot randomized. Serious flaw and risk of confounding by picking intervention schools where already 'trained to administer' intervention in past (acknowledged).
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used at 3 and 6m follow-ups, "across the 3-month and 6-month observations, there was high agreement between self-report and carbon monoxide-validated quit rates"
Incomplete outcome data (attrition bias)
All outcomes
Unclear riskApprox 50% available at 12m follow-up but reports on multiple studies, rates of dropout not specified for this particular site
Other biasHigh riskNon-significant difference at 15m caused by doubling of control quit rate between 6m and 15m. This may be partly attributable to Master Settlement Agreement funding of US$5.8 million administered across the state for prevention activities, which confounded the background rate.

NoT WV 2011

MethodsCountry: United States
Setting: 99 Public High schools in West Virginia
Study design: Cluster controlled trial. Intervention schools were allocated to either NoT alone or NoT plus a physical activity programme. This enabled comparison of NoT with NoT plus FIT.
ParticipantsParticipants: 233 participants (I 170, C 63). NoT alone had 90 in intervention group and NoT plus FIt had 80 in Intervention group
Age range: 14 -19yrs
Criteria for inclusion: ≥ 1 day of smoking in last 30 days
Inducements to enter study: None
Pre-study smoking status assessment: Self reports
Post study smoking status assessment: Self reports plus breath CO at 3 months but self reported only at 6 months
Interventions

NoT intervention with Brief Intervention as control. See NoT FL 2001 for details.

NoT plus FIT participants were given a pedometer and encouraged to keep a log of steps taken.

Outcomes

Measurement: 7 day point prevalence abstinence at 3 months, self reported quitting at six months
Biochemical verification: breath CO at 3 months

Losses to follow-up: > 60% of participants retained

NotesNew for 2013. Although results analysed as clusters, 21 (out of 40) schools dropped out after randomisation but before study onset due to recruitment and logistics. We note that the abstract gives impression that 7 day PPA is measured at 6 months. However outcome at 6 months is self report only.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskComputer based randomization
Allocation concealment (selection bias)High risk21 out of 40 schools dropped out after randomization but prior to study start, aware of assignments.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNo information specified, unclear if arms knew what other arms were receiving
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation of outcomes
Incomplete outcome data (attrition bias)
All outcomes
Low risk> 60% followed up, participants lost to follow up counted as smokers

Patten 2006

Methods

Country: USA
Setting: Community-based in three locations; Minnesota, Winsconsin and Conneticut.

Study Design: Randomized controlled trial

Recruitment: Community based recruitment by television commercials, radio, newspaper announcements and flyers in schools and clinics

Participants

Participants: 139 Smokers: (I 70; C 69 )
Age range: 11-18 years, median 16 yrs
Criteria for inclusion: Smoked > 10 cigarettes in previous 30 days, primarily used tobacco, parental consent given
Follow-up method: Clinic visits at 4,8,12,24 and 36 weeks
Pre study Status assessment: Modified Fagerstrom=4.1±1.9, mean cpd 10.1±6

Inducments to enter study: US$10 per visit for weeks 4 to 24 for completed visits, US$20 at week 36.
Post study smoking status assessment: self reports validated with CO measurement
Significant demographic differences between arms of the trial:None

Interventions

Intervention: Stomp out Smokes delivered by home based Internet and using as theoretical base Social (cognitive) Learning theory, health communication and decision-making theories. Access to SOS was available for 24 weeks after enrolment. No clinician contact except during assessment clinic visits

Control: Brief Intervention (office based) developed by American medical Association and delivered by counsellor at four individual weekly sessions

No participants required to set quit dates and pharmacotherapy not provided.

OutcomesMeasurement: 30-day PPA at 24 weeks and 36 weeks.
Verification: Self reports plus CO validation
Losses to follow-up: 33% at week 24 and 43% at week 36
NotesAs intervention was available up to 24 weeks point outcomes taken from 36 weeks as more realistically demonstrating persistence of intervention.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomly assigned," method of sequence generation not specified
Allocation concealment (selection bias)Unclear riskNo details provided
Blinding of participants and personnel (performance bias)
All outcomes
Low riskDue to nature of intervention any contact likely to be part of intervention, so performance bias unlikely. "Except for the assessment visits, study staff did not have any personal contact with participants."
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
Low riskThe percentage attending assessment visit in the intervention and control conditions, respectively, was 42 and 53% at 9m. All randomized participants included in ITT analysis which produces more conservative outcome.

Peterson 2009

MethodsCountry: USA
Setting: High Schools in Washington State
Study Design: Matched pair randomized (at school level) controlled trial
Recruitment: Following smoking status baseline survey in all schools smokers were invited to participate in intervention. Non-smokers also invited to preserve confidentiality of students.
ParticipantsParticipants: 782 Smokers: (I 414; C 368 )
Age range: 16-18 years,
Criteria for inclusion: See Notes as restricted subset. Parental consent sought.
Follow-up method: Questionnaire at 12 months from intervention.
Pre study Status assessment: Self-designed four item scale, mean cpd 10.1±6
Inducements to enter study: US$10 per completed post-study questionnaire (US$20 if survey returned at second or third prompt)).
Post study smoking status assessment: self reports .
Significant demographic differences between arms of the trial: Random assignment but Experimental group contained higher proportion of daily smokers (statistically corrected in analysis)
InterventionsIntervention: Complex intervention including quit kit, tailored telephone counselling, supportive website (TTM based) and school-wide cessation health promotion campaign. Specific attributes of teen smoking addressed, e.g. need for privacy, confidentiality and sense of being in control, state of motivation, importance of peer support
Theoretical basis of intervention: TTM, Motivational Interviewing, CBT and social cognitive theory based counselling
Control: Normal school based activity
OutcomesMeasurement: Self reported 6 month continuous abstinence.
Verification: Self reports. No biochemical validation but internal within-questionnaire validity checks on reports of smoking status
Losses to follow-up: 11% at week 52 after intervention
NotesAuthor supplied data on outcomes as inclusion criteria for this review is smoking at least 1 cigarette per week for six months. Whole study included smokers who had smoked at least 1 cigarette in the last 30 days or time since starting. This analysis uses the study subset "current daily smokers at baseline". This is more restrictive than our own criteria and it is this group that is recognised, in the literature, as most likely to be addicted.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low riskMatched-pair randomization for individual schools, "schools were randomly ordered within each matched pair, and then, one school in each pair was randomly assigned to the experimental or control condition by a computerized coin flip."
Allocation concealment (selection bias)Low riskComputerized coin flip "performed openly, witnessed, and recorded"
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"The tracking and data collection staff were blind to experimental vs. control status at outcome data collection and entry." As control was normal school based activity, performance bias unlikely.
Blinding of outcome assessment (detection bias)
All outcomes
High riskNo biochemical validation used, intervention higher intensity than control, differential misreport possible.
Incomplete outcome data (attrition bias)
All outcomes
Low risk91% control and 87% intervention completed follow-up survey, ITT analysis conducted.

Project EX Russia 2013

MethodsCountry: Russia
Setting: Summer Recreational Camps
Study design: Cluster randomized controlled trial
ParticipantsParticipants: 164 Smokers (I 76, C 88)
Age range: up to 19 years old
Criteria for inclusion: at least one cigarette per week for at least 6 months prior to enrolment
Follow-up method: At 6 months through telephone calls and emails
Pre study Status assessment: Self reported
Inducements to enter study: None
Post study smoking status assessment: Self reported
InterventionsIntervention: Standard Project EX (see Project EX-1 2001)
Theoretical basis of intervention: Complex intervention including CBT and motivational enhancement.
Control: standard care on tobacco use (officially tobacco use not allowed during camp)
OutcomesMeasurement: Self reported
Biochemical verification. None
Losses to follow-up: 34 out of 164 (I=16, C=18)
NotesNew for 2013.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Low risk

"experimental pilot trial that involved different youth that rotated through camps. Conditions were nested within camps. Two rotations of unique subject groups of smokers (program and standard care control) through each of five camps provided the means of controlling for campsite by condition"

Allocation decided by coin toss.

Allocation concealment (selection bias)Unclear riskInsufficient detail reported
Blinding of participants and personnel (performance bias)
All outcomes
Low risk"Youth in a given rotation were informed that they would be offered assistance in quitting smoking. However, they were kept blinded to study condition, which was easy considering that totally different cohorts of youth attended the different camp rotations."
Blinding of outcome assessment (detection bias)
All outcomes
High riskIntervention involved face-to-face contact, no biochemical validation of smoking status
Incomplete outcome data (attrition bias)
All outcomes
Low riskLow loss to follow up in both conditions

Project EX-1 2001

MethodsCountry: USA
Setting: 18 Continuation high schools in southern California
Study design: Cluster randomized controlled trial (assigned by block randomization)
ParticipantsParticipants: 335 smokers, recruited by advertising and flyers within each school. 139 in 6 Project EX schools, 120 in 6 Project EX plus SAC schools, 76 in 6 control schools.
Age range: 14-19 yrs Mean age was 16.8 (± 0.8) years.
Criterion for inclusion: used tobacco in last 30 days.
Follow-up method: Questionnaires and telephone for those who had left school
Inducements to enter study: class credits and class release time
Pre-study smoking status assessment: Questionaire. Mean smoking 8.8cpd ( ± 9.3) Modified Fagerstrom scores 30% in range 0-6, 53% in range 7-13 and 17% in range 14-21.
Post study smoking status assessment: questionnaires
No significant demographic differences between arms of trial
InterventionsIntervention: Initially schools split into three arms: (1) Project EX sessions alone (clinic only schools). (2) Project EX plus school community development 'school-as-community' (SAC schools). (3) Control: standard care.
1. Project Ex is 8 sessions or 'clinics' over a 6-week period delivered to groups and developed in trials. Four sessions are preparation for quitting over 2 weeks, and next 4 are weekly during the first month post-quit.
Theoretical basis of intervention: Complex theoretical constructs including motivation interviewing etc, and including games for groups, education and anger management, yoga, weight control, meditation, assertiveness training, role play and relapse prevention.
2. SAC intervention: modelled on Toward No Drug Abuse programme. Student body organised service, recreational and job training functions, and produced a Project newsletter, to enable expression of anti-tobacco attitudes.
Outcomes

Measurement: 30-day PPA; Follow-up periods: >3m, 6m from start of study.
Verification: CO (for 62 students and results adjusted by false quit reporting factor of this group)
Losses to follow-up: 51% in intervention group - 40% of intervention group dropped out during clinics - 42% in control group lost to follow-up. Results:
No difference in outcomes between two intervention arms of trial so authors pooled data and compared, as a single arm with control arm.
Calculated OR based on 17% in intervention = 44 people and 8% in control being 6 people*
Calculated OR = 2.388 (0.976 to 5.841)

Details from authors:

NotesRecruitment in intervention arm was voluntary; 90% of subjects said they had volunteered because they wanted help with quitting
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear risk"Randomized block design procedure," method not specified
Allocation concealment (selection bias)Low riskStudents recruited after schools randomized
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used for 62 students and results adjusted by false quit reporting factor of this group
Incomplete outcome data (attrition bias)
All outcomes
Low riskPer-protocol analysis and ITT analysis yield similar outcomes, "evidence that the study findings are robust despite the relatively high clinic drop-out rate."

Robinson 2003

MethodsCountry: USA
Setting: 18 schools in Memphis, Tennesee
Study design: Randomized controlled trial
ParticipantsParticipants: 316 smokers referred to study by school administrators or parents after violation of school no smoking policy, 261 students (I 169; C 92) followed up so far [2006].
Age range: 13-19 year olds; 64% male.
Follow-up method: Telephone assessment, self-reporting
Inducements to enter study: Fast food coupons, discounts at music stores and money on completion.
Pre-study smoking status assessment: mFTQ
Significant demographic differences between arms of trial: More cases in intervention than control arms because of school wish to have offenders treated.
InterventionsIntervention: 4 x 50-minute sessions behavioural programme, based on STS (Start To Stop) model, of motivational interviews at start of programme and monthly phone calls for 1 year to assess smoking status and give brief support, based on stage of change.
Theoretical basis of intervention: Social influence theory, motivational enhancement, CBT and TTM
Control: Written material at start of study, and monthly phone calls to assess smoking status.
OutcomesMeasurement: 7-day PPA; Follow-up periods: >3m, 12m.
Verification: Attempted for all quitters. Salivary cotinine samples obtained for 18/41 cases, CO initially as a 'bogus pipeline' for some students.
NotesPaper based on incomplete follow-up and denominators unclear so data not shown in comparisons. No evidence of effect detected. We were unable to obtain clarification from authors
Stratified data available on baseline characteristics
Referral to study for violation of school no smoking policy raises issues of consent.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskRandomization at individual level, method not specified
Allocation concealment (selection bias)Unclear riskNot specified
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified
Blinding of outcome assessment (detection bias)
All outcomes
Low riskBiochemical validation used (indicating that 50% of those who had reported quitting had falsified smoking status)
Incomplete outcome data (attrition bias)
All outcomes
Unclear risk92% retention but rates in each group not clear
Other biasUnclear riskPossible contamination as unit of allocation was student, so that controls and interventions mixed in same schools, and there was no concealment of allocation.

Sherbot 2005

MethodsCountry: Canada, Nova Scotia
Setting: Intervention introduced into a wider programme set up for young people who had been identified as having substance abuse problems (including drugs, alcohol and gambling but not tobacco).
Study design: Randomized controlled trial
ParticipantsParticipants: 39 young people, 13 in each study group referred onto programme from both urban and rural settings
Age range: 13 - 19 years
Criterion for Inclusion: Enrolled on "Choices Adolescent Treatment Program" and not taking any psychotropic drugs
Inducements: Wait list received 2x $25each and intervention groups 4x $25 each. All completing participants at 7/12 received $25
Follow-up method: Participants contacted by phone or mail
Pre-study smoking status assessment: FTND
Post study smoking status assessment: Self reported quitting & FTND
InterventionsIntervention: Group A - Motivational Enhancement therapy delivered over a period of four weeks at one session per week
Intervention: Group B - Completion of "Quit 4 life" booklet over a period of four weeks at two sessions in the first week, two sessions in the second week, two sessions in the third week, and three sessions in the fourth week
Theoretical basis of intervention: Motivational interviewing
Control: On waiting list
OutcomesSelf reported quitting at 6 months; Group A 5; Group B 1; Control: 2
Losses to follow-up: Overall 10.3%, Group A 2.6%, Group B 2.1%, Group C 2.7%
NotesAll referrals to both programme and this study were voluntary. 100% of those studied also used marijuana. Quitting data not verified and large differences between intervention groups in baseline smoking reports, possibly explained by outliers.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)High risk'Participants had the opportunity to draw either an “A,” “B,” or “C” to determine which group they were to be in'
Allocation concealment (selection bias)High riskNo possibility of concealment
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified but due to nature of intervention, performance bias unlikely
Blinding of outcome assessment (detection bias)
All outcomes
High riskNo blinding reported, no biochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
Low risk4/39 lost at 6 months
Other biasHigh riskLarge differences between intervention groups in baseline smoking reports, possibly explained by outliers.

Woodruff 2007

  1. a

    C: Control Group
    CBT: cognitive behavioural therapy
    CO: Carbon monoxide
    cpw: cigarettes per week
    FTND: Fagerstrom Test for Nicotine Dependence
    mFTQ: modified Fagerstrom tolerance questionnaire
    I: Intervention Group
    m: month(s)
    PPA: point prevalence abstinence
    TTM: Transtheoretical model (stages of change)

MethodsCountry: USA, San Diego County
Setting: 14 schools
Study design: Cluster Randomized controlled trial
ParticipantsParticipants: 136 young people volunteering, (I 77 ; C 59)
Age range: 14 years to 19 years
Criterion for Inclusion: volunteering and consented (parents and teenagers) and smoking at least one cigarettes within the last 30 days
Inducements: Participants were asked to complete an an-line survey and paid (sum in brackets) on completion of survey at baseline($5), immediate post intervention ($10), 3 months post completion ($15) and 12 months post completion ($20)
Follow-up method: Completion of on line survey with reminders
Pre-study smoking status assessment: Self reported
Post study smoking status assessment: Self reported quitting
InterventionsIntervention: Web-based virtual reality world based on sky mall with students as avatars and counsellor present as avatar. Information represented as "shops" and galleries and chat possible as more than one student can be "present". Chat texted based at foot of screen. Students also offered one-to-one counselling sessions with Smoking Cessation professional
Theoretical basis of intervention: Motivational interviewing and responses in virtual world based on social cognitive theory
Control: Asked to complete on-line surveys with inducements.
OutcomesSelf reported quitting at one year; Intervention Group: 19 Control: 18
Losses to follow-up: Overall 27.2%, Intervention Group: 32.5%, Control Group: 20.3%
Notes'Effects of clustering were small' so analysis at individual level.
Risk of bias
BiasAuthors' judgementSupport for judgement
Random sequence generation (selection bias)Unclear riskCluster randomized by school, method not described
Allocation concealment (selection bias)High riskStudents recruited after schools randomized, with different recruitment methods. The two conditions did not differ significantly on demographic data, although a significantly greater proportion of intervention subjects were alternative/continuation high school students. The groups differed significantly on several baseline smoking variables.
Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskNot specified but due to nature of intervention, performance bias unlikely
Blinding of outcome assessment (detection bias)
All outcomes
High riskNo blinding reported, no biochemical validation used
Incomplete outcome data (attrition bias)
All outcomes
Low riskLoss to follow-up was 25% post-intervention, 21% for the 3-m follow-up survey, and 27% at 12 months. Survey non-response was higher among intervention participants then among controls (33% vs. 15%). All randomized participants included in ITT analysis.

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion
Abelin 1989NRT double blind randomized trial for 112 young people. Reported follow-up was for three months only.
Abroms 2007Although strictly speaking the age range of the subjects in this study fall within those of interest to us, the mean age of subjects was 19.8 years and the population was a sub-set in higher education. We have excluded this study therefore but note the results OR:1.92 (95th % CI:0.35 to 10.52)
Adelman 2000RCT of a psycho-social intervention targeted at young people. Although measurements made at 6 months follow-up the control group were given the intervention three months after the intervention group, therefore only three month effectiveness data is available.
Adelman 2009NCT of nasal spray for 6 weeks plus counselling vs counselling alone. Unpleasant adverse effects, poor adherence, and consequent lack of efficacy did support the use of nicotine nasal spray as an adjunct to counselling. Outcome reported at 12 weeks therefore not added to review.
Ames 2007Median age of study subjects is 20 years with range 18-21 years. This age range is outside scope of this review.
An 2007Evaluates recruitment strategies, not smoking cessation
Audrain-McGovern 2011Although a cessation trial the intervention group could choose reduction rather than cessation as an outcome. Not added to data as not a pure cessation trial.
Audrey 2008Smoking prevention programme, not cessation
Bauman 2000The authors state that there were "no activities focused explicitly on cessation or reduction " in their intervention.
Bloor 1999Controlled trial using pupil advocates but only three month follow-up.
Bond 2004No discrete cessation component or results.
Bramley 2005Subjects of study outside age range of review
Braverman 1994Report not found but unlikely to be a trial
Brendryen 2008Trial of internet based support over 12 month period for over 18 year olds. Self reports of abstinence used with no verification. Main outcome repeated reports of abstinence at 1, 3, 6 and 12 months.
Burton 1994This is a report of the secondary cessation component/effects of the Project TNT intervention designed as a preventative programme. Follow-up is 4 months after start of trial. Summary paper published in 2009.
Cai 2000Intervention over 4 weeks and follow-up of cases for further three months. Excluded as not having six month follow-up but results from three months give no evidence of effectiveness:
1/12 (end of treatment OR=1.027 (0.57-1.84) and 4/12 from beginning of study = OR 0.971
(0.53-1.77)
Campbell 2008This trial was not designed as a pure cessation intervention.
Cavallo 2007Preliminary data giving end of treatment rates of cessation but no long term follow-up
Chen 2006Follow-up only 4 weeks so not eligible for this review
Colby 1998RCT of brief motivational interviewing in a hospital setting. Follow-up at three months so not eligible for this review.
Digiusto 1994This study, a "quasi-experiment" with pair matching for analysis, describes two interventions (same intervention but different time of delivery) and control. Control data on quitting collected at 6 months but data from one intervention arm collected at approximately 19 weeks after allocation.
Dino 1998West Virginia NoT with 3 and 4 month follow-up data from baseline
Egger 1983Community intervention, with cessation component and control population, aimed at adults in community over age of 18 years. Although subset of population this study was not aimed primarily at young people.
Ehrsam 1991Average age of participants in intervention group 21.9±6.8 years and control 24.1±6.9 years. Small size of overall study groups (56 cases in each arm) would mean it would be difficult to extract meaningful outcomes from sub-group analysis for age range of this review.
Elsasser 2002Conference paper: Trial of only 17 cases randomized to treatment or control therefore very underpowered. Outcome measured at 3/12.
Emmons 2003This study was long term follow-up of children who had had cancer. Current age of participants was 31±6.6 years.
Erol 2008Uncontrolled before and after study.
Escoffery 2004Phrogramme aimed at college students over 18 years of age. Average age of participants was 21 years.
Faessel 2009Clinical trial of safety and tolerability and pharmacokinetics of 14 days of high dose varenicline. Study design did not include cessation outcomes.
Fagan 2003This was an RCT designed to control tobacco use amongst young people and based in the workplace. Outcomes were reduction of use and intention to quit measures rather than actual cessation.
Figa-Talamanca 1989Educational RCT aimed at whole class groups and not specifically smokers.
Flay 1995Primarily a prevention programme and measured outcomes were in terms of knowledge and intention to quit. Cessation component not discrete.
Gray 2011A trial of sustained release bupropion combined with contingency management. The primary outcome was 7-day cotinine-verified point prevalence abstinence but follow-up was only for 12 weeks.
Hamilton 2005A school based cluster randomized controlled trial designed to test a harm minimisation approach. Only prevalence data available, no discrete results for smokers.
Hancock 2001Trial of community intervention aimed at teenagers that reported population prevalence of smoking rather than following up individual smokers.
Hanson 2003Trial of NRT(patches) for 13-19 year olds. Abstinence reported at 10 weeks post quit date.
Hanson 2006A harm reduction study rather than cessation.
Harris 2010This study was aimed at young adults. The mean age of participants was 19.4yrs in a range 18 to 22 years.
Haug 2009Study of SMS intervention for young adults. Mean age = 25 years.
Heikkinen 2009Finish study of smokers aged 15-16. Two intervention groups, information and support offered by dentist or school nurse. Only 3 month follow-up.
Hellmann 1988Although (quasi) experimental in design there was no formal randomization or attempt to case match and baseline characteristics have not been assessed or compared.
Helstrom 2004Potentailly interesting study with positive results but follow-up only 5 months in initial report.
Higgs 2000This primarily a prevention trial reporting secondary cessation effects.
Hollis 1994Not targeted at regular smokers and discrete quitting data not available.
Horn 2004Report of West Virginia trial with 3 month follow-up data only.
Hort 1995In prevention review. No discrete cessation programme.
Jason 1982This is essentially a trial of two whole class prevention strategies.
Josendal 1998Primarily a prevention study.
Kang 2005Excluded as follow-up is 4 weeks.
Kealey 2009Telephone counselling intervention (Motivational Interviewing and CBST) with matched pair design.
Kelleher 1999Smoking cessation was a component of an intervention to reduce cardiovascular risk. No discrete results measured.
Kentala 1999Intervention by dentists to discuss smoking during annual check up. Young people randomized to brief intervention or normal care. Prevalence data only collected. Individual smokers not followed up.
Killen 1988This is a cardiovascular health promotion trial with a smoking cessation component but without discrete results for individual smokers.
Kim 2004No discrete cessation component in report.
Krishkowy 2008Prevention study.
Lando 2007Study experienced some recruitment issues and it is not clear that all participants were active smokers.
Lotecka 1983Cognitive Behavioural intervention trialled in four schools. No discrete results available and follow-up three months.
McCambridge 2004Follow-up of smoking component was 3 months only.
McCuller 2006Project EX intervention that reports 3 month follow-up.
Mermelstein 2006Follow-up 3 months only.
Myers 2008Although a smoking cessation intervention, it is targeted at and outcomes recorded for other substances.
Niederhofer 2004Trial of bupropion versus placebo. Effectiveness measured at 90 days (three months).
Norman 2008No discrete quit data available. Confirmed with author.
O'Neill 2000Computer-based intervention using stage change model. The mean age of participants was 19.7 years range 18 years to 25 years. This falls outside our definition for this review.
Pallonen 1998This was a comparison trial between two interventions. There was no control group randomized to "placebo"/no intervention. The authors state "The inclusion of two different interventions (for smokers) rather than a treatment/control comparison is for process analysis since the sample size was inadequate for a clinical trial." The number of smokers in study was 135.
Pbert 2006Excluded as follow-up only 3 months.
Pbert 2008Not specifically targeted at smokers and no discrete results available at this time.
Perry 1980This is primarily a prevention study as the stated aim is to influence the incidence of smoking. The results are presented in such a form that overall prevalence is measured for a whole year group and discrete smokers cannot be identified.
Quinlan 2000Clinical trial using intervention matched to stage of change (TTM). Age range 18 years to 55 years. Mean age by group of participants was 20.41 yrs, 21.71 and 23.3 years and therefore this study falls outside the scope of this review.
Rabius 2004The age range of this study includes a cohort of 18 to 15 year olds. it is not possible to disaggregate 18 and 19 year olds from report of study but author contacted for primary data. If available this data will be incorporated in future versions of review.
Rice 2010Study based on Project TNT. Non random allocation instead compared cohorts in different years.
Roddy 2006Although this study meets all other inclusion criteria the outcome is measured at 13 weeks. This review uses Russell Standards, i.e. a minimum of a 6 month follow-up.
Rubinstein 200812 week follow-up only.
Schepis 2006Excluded as outcome is measured at 4 weeks.
Severson 1991Essentially a prevention study.
Simmons 2011Test of web-based intervention in American college students, participants older than 18.
Sims 2011Reports outcomes for young adults aged 18-24; average age not reported but over 20. Original study intended to recruit adolescents smokers but low recruitment, and results for 52 adolescents not reported.
Solomon 2009Outcomes long term prevalence of smoking.
Stein-Seroussi 2009Cluster randomised trial including biochemical verification of cessation. Outcome reported after 90 day follow-up.
Stephens 2001Good quality trial of Motivational Enhancement for young people but follow-up only 30 days at end of an intervention of 5 weeks duration. Author notes a high drop out rate.
Stoddard 2005Prevalance only measured, no discrete cessation data.
Sussman 1995This is a trial of Project TNT, an intervention based on cessation intervention clinics. Outcomes are self reported at 4 months after start of intervention.
Sussman 2007No discrete quitting data available. Authors contacted. Quitting rates, adjusted for mFTQ, given as 15% for programme group and 8% for control group.
Travis 2009Excluded as aimed at college students with participants median age 21±3 years and only 3 month follow-up.
Turner (NOT) 2006A version of NoT with web based component added. Only 3/12 follow-up.
Wang 2006Not a trial of intervention but a correlation analysis.
Werch 2008Trial of brief, image based multiple behaviour intervention for adolescents and college students. Aimed at range of substance abuse.Three month follow-up.
Whittaker 2011Although recruiting over 16 years of age, mean age of participants was 27 years +/- 8.7
Winkleby 2004Programme aims were to reduce smoking and although gives 6/12 follow-up discrete results not available for individual smokers as unit of analysis was school.
Wongwiwatthananukit 2009Trial of pharmacist-based cessation programme for youth offenders, one arm voluntary cessation one arm compulsory cessation. Excluded as non-randomised allocation as part of criminal justice process.

Characteristics of studies awaiting assessment [ordered by study ID]

Minary 2009

MethodsQuasi-experimental study in 8 vocational training centres
Participants1,814 students, at baseline 52% were smokers and 5.7% ex-smokers
InterventionsTABADO program, which included a general information session for all students and small-group sessions plus individual counselling and nicotine therapy, if needed, for volunteers in an enhanced program. The control group received no specific intervention other than the educational services usually available. .
OutcomesThe primary outcome was 30-day point prevalence abstinence at 12 months
NotesResults published after date of searches

Characteristics of ongoing studies [ordered by study ID]

Arora 2010

Trial name or titleProject ACTIVITY
MethodsRandomised controlled trial
ParticipantsParticipants recruited from 14 slum communities in Delhi, India
InterventionsMultiple strategies including community training for peer leaders and activists, community based interactive activities and outreach programmes such as films and street rallies, comic books and sticker cards, community based clinics and face-to-face counselling
OutcomesRates of tobacco use, past 6 months and 30 days smoking history, cessation rates
Starting datenot specified
Contact informationMs. Monika Arora, Director HRIDAY (Health Related Information Dissemination Amongst Youth). Address
for Correspondence: HRIDAY, C-1/52, 3rd Floor, Safdarjung Development Area, New Delhi-110016, India, monika@hriday-shan.org, monika.arora@phfi.org, Telephone No: 91-11-26850342;91-41031191, Fax No: 91-11-26850331.
NotesAdded 2013

Varenicline-NCT01312909

Trial name or titleSmoking Cessation in Healthy Adolescent Smokers
MethodsRandomised control trial
ParticipantsHealthy smokers aged 12-19
InterventionsVarenicline 1mg bd, 0.5 mg bd or placebo
OutcomesReduction or abstinence through to week 52
Starting dateTBC
Contact informationPfizer 1-800-718-1021
NotesAdded 2013

Ancillary