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Silicone gel sheeting for preventing and treating hypertrophic and keloid scars

  1. Lisa O'Brien1,*,
  2. Daniel J Jones2

Editorial Group: Cochrane Wounds Group

Published Online: 12 SEP 2013

Assessed as up-to-date: 8 MAY 2013

DOI: 10.1002/14651858.CD003826.pub3

How to Cite

O'Brien L, Jones DJ. Silicone gel sheeting for preventing and treating hypertrophic and keloid scars. Cochrane Database of Systematic Reviews 2013, Issue 9. Art. No.: CD003826. DOI: 10.1002/14651858.CD003826.pub3.

Author Information

  1. 1

    Monash University, Occupational Therapy, Frankston, Victoria, Australia

  2. 2

    University of York, Department of Health Sciences, York, UK

*Lisa O'Brien, Occupational Therapy, Monash University, PO Box 527, Frankston, Victoria, 3199, Australia. lisa.obrien@med.monash.edu.au.

Publication History

  1. Publication Status: New search for studies and content updated (no change to conclusions)
  2. Published Online: 12 SEP 2013

SEARCH

 

Background

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

Wounds, such as burns, surgical incisions and ulcers, are repaired through the deposition of components that form new skin. These components include blood vessels, nerves, elastin fibres (which give the skin some elasticity) and collagen fibres (for tensile strength), as well as glycosaminoglycans (GAGS) which form the gel-like ground substance (or matrix) in which the structural fibres, nerves and blood vessels are embedded. In the early stages of healing, a cicatrix is formed. The cicatrix consists of a thin layer of skin (the pellicle) that covers the wound and subsequently contracts and becomes paler in colour, forming the scar.

Some scars develop abnormally, giving rise to keloid and hypertrophic scars. The scars arise from an excessive proliferation of dermal tissue following skin injury, with keloid scars developing in 5% to 15% of wounds (Wittenberg 1999). This proliferation of dermal tissue is due to both the production of fibrous tissue (fibroplasias) and the accumulation of abundant and randomly organised new collagen bundles.

O'Sullivan 1996 observed that although the terms 'keloid' and 'hypertrophic' have often been used synonymously, the two sorts of scarring are, in fact, significantly different. The principle clinical feature that distinguishes them is that in keloid scars the scar tissue progressively encroaches upon the normal skin surrounding it, producing a scar that appears irregular and pendulous in areas. Conversely, the hypertrophic scar is confined to the tissue damaged by the original injury. This type of scar increases in dimension by pushing out its margins, rather than invading surrounding tissue. Clinicians usually base diagnosis of keloid scarring on the overgrown boundaries and delayed onset of the scar (hypertrophic scars develop soon after injury) (Shaffer 2002).

Keloid scarring is reported to be more common in darker skin (Beers 1999; Niessen 1998), while hypertrophic scarring is more common in fair skin (Beers 1999). Examination of scars with an electron microscope shows keloid collagen to be thin and irregular with cross-striations, suggesting immaturity, while keloid scars are deficient in lymphatics and their associated elastic fibres, and have a higher content of both water and soluble collagen than normal skin. Although hypertrophic scars have similar qualities in the early stages, after seven months the two become distinct as the water and collagen content of hypertrophic scars normalises (Raney 1993).

Hypertrophic scars tend to follow surgery and thermal injuries such as severe burns (Carney 1993; Eisenbeiss 1998; Shakespeare 1993), whereas keloid scars often originate after trivial injury such as ear piercing, insect bites and vaccination. The amount of scar tissue in a keloid scar exhibits little relation to the extent of the injury that caused it (O'Sullivan 1996).

Both types of scarring can cause functional and psychological problems for people, and their management can be difficult. Treatment options have included surgery, radiation therapy, steroid injections, pressure therapy, cryotherapy (treatment with liquid nitrogen) and laser therapy (Shaffer 2002). Many surgical techniques have been applied to remove keloids, either alone, or in combination with other treatments. Surgery alone has shown a high recurrence rate (Raney 1993).

Scars in specific sites of the body, including the lower face, presternum, pectoral area of the chest, upper back, ears, neck and outer (deltoid) area of the upper arms are more likely to develop abnormally (O'Sullivan 1996). People with scars in these high-risk anatomical areas, or with a history of forming keloid scars, aim to prevent further scarring by observing certain principles that include: avoiding non essential cosmetic surgery, closing all wounds with minimal tension, and using pressure garments for four to six months after injury or surgery (O'Sullivan 1996).

The use of topical silicone for prevention and treatment of hypertrophic scarring is still relatively new. Silicone was first used, in gel form, for the treatment of burn scars at Australia's Adelaide Children's Hospital in 1981 (Perkins 1982). Silicone has since been produced in various forms, including: silicone cream compounds (Sawada 1992); silicone oil or gel with additives such as vitamin E (Palmieri 1995); in combination with other dressing media (Davey 1991); and as custom-made silicone applications. This particular review is solely concerned with commercially produced adhesive silicone gel sheeting.

Silicone gel sheeting is a soft, self adhesive and semi-occlusive sheet used for the treatment and prevention of both old and new hypertrophic and keloid scars. It is made from medical-grade silicone (cross-linked polydimethylsiloxane polymer) and reinforced with a silicone membrane backing (Katz 1992; Thomas 1997) thought to give it increased durability and make handling easier (Williams 1996).

Silicone gel sheeting is designed to be used on intact skin. It should not be used on open wounds and, according to the product information sheet supplied by the manufacturers (Smith & Nephew 2000), is contraindicated in people with dermatological conditions that disrupt the integrity of the skin (for example, severe acne or psoriasis).

The mode of action of silicone-based products on scar tissue is unknown. Some researchers suggested that silicone may penetrate the skin, but studies by Ahn 1989 and Swanson 1974 found no evidence of silicone in the scar or stratum corneum. Quinn 1985 found that there was no significant difference in pressures obtained at the scar surface beneath the gel, and also concluded that there was no difference in scar surface temperature and oxygen tension, or water vapour transmissivity of the gel.

The cost of silicone gel sheeting (AUD 139 (Australian Dollars) recommended retail price for a 12 x 15 cm sheet, AUD 74 for a 12 x 6 cm sheet) may be moderated by the fact that, after rinsing, it can be reused by the patient or their carer. However, the fact remains that clinicians and funders of care will require clear evidence of its clinical effectiveness before recommending its use.

 

Objectives

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

The aim of this systematic review was to determine the effects of silicone gel sheeting in the:

  1. prevention of hypertrophic or keloid scarring in people with newly healed wounds (e.g. post surgery); and
  2. treatment of established scarring in people with keloid or hypertrophic scars after any type of wound.

 

Methods

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms
 

Criteria for considering studies for this review

 

Types of studies

Any randomised controlled trials (RCTs) or quasi-randomised controlled trials (QRCTs) (method for allocating participants to a treatment that is not strictly random, e.g. by date of birth, hospital record number, alternation) or controlled clinical trials (CCTs) (where an intervention group is compared to a comparison or control group) of interventions.

 

Types of participants

People with healed full-thickness wounding (from any cause) where the skin was intact, with or without scarring at baseline.

 

Types of interventions

All comparisons of silicone gel sheeting with other conservative techniques (e.g. hydrocolloid dressings, non silicone gel sheeting, laser therapy or no intervention) were eligible.

We excluded comparisons of silicone gel sheeting with surgery. We excluded trials that reported only the absorption of silicone by the skin, but did not measure the effect on scar appearance.

 

Types of outcome measures

 

Primary outcomes

 

Prevention studies

The primary outcome measure was the number of people who developed keloid or hypertrophic scarring as determined by blood flow, hyperpigmentation, erythema (redness), scar thickness and regularity of scar.

 

Treatment studies

The primary measure was change in scar size (measured by area, length, volume, height, or width - usually by ruler, taking an impression, or ultrasound).

 

Secondary outcomes

 

Prevention studies

Other measures of clinical outcome:

  • scar size (measured by area, length, volume, height, or width - usually by ruler, taking an impression, or ultrasound);
  • scar colour (measured against standard colour charts), blood flow (measured using laser-Doppler flowmetry) and scar appearance (measured on a three or five-point scale with appropriate definitions);
  • skin elasticity (measured serially with the use of an elastometer);
  • development of complications (e.g. rashes, skin breakdown, measured on a numbered scale);
  • cosmetic appearance (cosmesis) as defined by patient opinion (using assessment scales) and physician observations;
  • patient tolerance, measured by reported side effects and adverse reactions;
  • preference for different modes of treatment, measured by patient choice after receiving at least two different types of treatment;
  • compliance, measured by physician and patient report.

 

Treatment studies

Other measures of clinical outcome:

  • scar colour (measured against standard colour charts), blood flow (measured using laser-Doppler flowmetry) and scar appearance (measured on a three or five-point scale with appropriate definitions);
  • skin elasticity (measured serially with the use of an elastometer);
  • development of complications (e.g. rashes, skin breakdown, measured on a numbered scale);
  • cosmesis as defined by patient opinion (using assessment scales) and physician observations;
  • patient tolerance, measured by reported side effects and adverse reactions;
  • preference for different modes of treatment measured by patient choice after receiving at least two different types of treatment;
  • compliance, measured by physician and patient report.

 

Search methods for identification of studies

For the search strategy for the first update of this review see Appendix 1.

 

Electronic searches

For this second update we searched the following databases in May 2013:

  • The Cochrane Wounds Group Specialised Register (searched 8 May 2013);
  • The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 4);
  • Ovid MEDLINE (2007 to April Week 4 2013);
  • Ovid MEDLINE (In-Process & Other Non-Indexed Citations, May 07 2013);
  • Ovid EMBASE (2007 to 2013 Week 18);
  • EBSCO CINAHL (2007 to 3 May 2013)

We used the following search strategy to search CENTRAL:

#1 MeSH descriptor: [Keloid] explode all trees 61
#2 MeSH descriptor: [Cicatrix, Hypertrophic] explode all trees 84
#3 MeSH descriptor: [Hypertrophy] explode all trees 1125
#4 keloid* or hypertrophic or cicatrix 1030
#5 scar or scars or scarred or scarring 2163
#6 #1 or #2 or #3 or #4 or #5 3712
#7 MeSH descriptor: [Silicone Gels] explode all trees 34
#8 silicone next gel* 89
#9 silicone next sheet* 17
#10 silicone next dressing* 18
#11 #7 or #8 or #9 or #10 114
#12 #6 and #11 59

The search strategies for Ovid MEDLINE, Ovid EMBASE and EBSCO CINAHL can be found in Appendix 2. We combined the Ovid MEDLINE search with the Cochrane Highly Sensitive Search Strategy for identifying randomized trials in MEDLINE: sensitivity- and precision-maximizing version (2008 revision) (Lefebvre 2011). The Ovid EMBASE and EBSCO CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (SIGN) (SIGN 2012). There were no restrictions with respect to language, date of publication or study setting.

 

Searching other resources

We examined the reference lists of relevant review articles and all included studies to identify further studies. We approached the major supplier of silicone gel sheeting (Smith and Nephew) for details of unpublished, ongoing and recently published trials. The search was not limited by language or publication status.

 

Data collection and analysis

 

Selection of studies

Two review authors (LOB, DJ) assessed the title and abstracts of potentially eligible trials independently. The review authors obtained papers that were potentially relevant and, using eligibility criteria, assessed their full text for inclusion independently. We resolved disagreements by discussion.

 

Data extraction and management

One review author extracted data and a second review author checked for accuracy. We used a standard data form to capture the following information:

  1. characteristics of the study (design, method of randomisation, withdrawals/dropouts, funding source);
  2. study participants (age, wound location, wound characteristics, scar type);
  3. intervention (silicone gel, non silicone gel);
  4. comparison intervention (e.g. laser therapy, compression, occlusive dressing);
  5. duration of treatment;
  6. outcome measures (type of scoring, timing of assessment, complications);
  7. duration of follow-up; and
  8. results.

We requested additional unpublished data from primary authors and included these when available.

 

Assessment of risk of bias in included studies

Only RCTs, QRCTs or CCTs were included in this review because of the increased risk of bias with other types of study. Two review authors independently assessed the methodological quality of the included studies using the Cochrane Collaboration tool for assessing risk of bias (Higgins 2011) and any disagreement was discussed amongst all review authors to achieve a consensus. The 'Risk of bias' tool addresses six specific domains, namely sequence generation, allocation concealment, blinding, incomplete outcome data, selective outcome reporting and other issues (e.g. extreme baseline imbalance) (see Appendix 3 for details of criteria on which the judgement was based). We assessed blinding and completeness of outcome data for each outcome separately, and completed a 'Risk of bias' table for each eligible study.

We have presented our assessment of risk of bias using a 'Risk of bias' summary figure (Figure 1), which presents all of the judgements in a cross-tabulation of study by entry. This display of internal validity indicates the weight the reader may give the results of each study.

 FigureFigure 1. 'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.

 

Assessment of heterogeneity

We explored clinical heterogeneity by examining potentially influential factors such as age of people, cause of scar (e.g. if from recent surgery) and age of scar before treatment commenced. When statistical pooling was done, we tested for statistical heterogeneity using the Chi² test. If clinical heterogeneity was suspected, we combined the studies by narrative summary only. In the presence of statistical heterogeneity (i.e. when the Chi² was greater than degrees of freedom) but where other factors suggest pooling was appropriate, we used a random-effects model. Otherwise we used a fixed-effect model.

 

Data synthesis

The comparisons are as follows.

  1. silicone gel sheeting compared with no treatment.
  2. silicone gel sheeting compared with non silicone dressing.
  3. silicone gel sheeting compared with other silicone products.
  4. silicone gel sheeting compared with laser therapy.
  5. silicone gel sheeting compared with triamcinolone acetonide injection treatment.
  6. silicone gel sheeting compared with topical onion extract.
  7. silicone gel sheeting compared with pressure therapy.

Data for prevention (i.e. for newly healed scars) and treatment (i.e. for existing keloid or hypertrophic scars) have been dealt with separately.

The analysis tables contain quantitative data from individual trial reports for prespecified outcomes and subgroups (e.g. those with a high risk of abnormal scarring versus normal population) for both dichotomous and continuous outcomes.

A narrative summary of results is presented. Results of dichotomous variables are presented as risk ratio (RR) with 95% confidence intervals (CI). We have used risk ratio rather than odds ratio, as event rates are high in these trials and odds ratios would give an inflated impression of the magnitude of effect. In addition, we have carried out statistical pooling on groups of studies which we considered to be sufficiently similar.

 

Results

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms
 

Description of studies

Searches for this second update identified 13 potentially relevant articles. Independent scrutiny of the titles and abstracts by both review authors identified five new studies that met the inclusion criteria, bringing the total number of included studies to 20. Reasons for excluding the other studies can be found in the Characteristics of excluded studies.

We contacted 11 authors for additional trial data and five (de Oliveira 2001; Niessen 1998; Li-Tsang 2006; Li-Tsang 2010; Niessen 1998; Wigger-Alberti 2009) kindly supplied these. We contacted the manufacturers of silicone gel sheeting (Smith & Nephew) and they supplied a categorised table of clinical trials conducted for key scar therapies. We checked this against the studies already sourced through the search strategy and ordered any papers not already considered, then subjected them to the same eligibility criteria as the other trials to determine whether they should be included. No further trials were identified from this source.

All 20 included trials compared silicone gel sheeting with either a control or another treatment. The studies were mainly single-centre studies, although one included data from four hospitals (Niessen 1998). The studies were conducted in eight countries, with most being conducted in either North America (seven studies) or in Europe (eight studies). Where there were multiple trials for the same first author, we inspected for independence of study populations and found that that all were separate groups of participants. Prospective trial registration with unique trial numbering would help avoid duplication in systematic reviews.

The 20 included studies involved a total of 849 people aged between 1.5 to 81 years. The 'Characteristics of included studies' table provides details of individual studies. No age limits were explicitly applied, however where information was provided, most participants were adult.

In three studies (de Oliveira 2001; Gold 1994; Niessen 1998) a distinction was made between keloid and hypertrophic scarring and the results were discussed separately.

The trials made the following comparisons based on the objectives (i.e. to determine the effectiveness of silicone gel sheeting in preventing and treating hypertrophic and keloid scars):

 
(1) Silicone gel sheeting compared with no treatment

There were three prevention studies (Cruz-Korchin 1996; Gold 2001; Niessen 1998) involving 245 people.
There were eight treatment studies (Ahn 1989; Carney 1994; Colom Majan 2006; de Oliveira 2001; Li-Tsang 2006; Li-Tsang 2010; Tan 1999; Wittenberg 1999) involving 219 people.
There were two studies that evaluated both prevention and treatment (Ahn 1991; Gold 1994) involving 82 people.

 
(2) Silicone gel sheeting compared with non silicone dressing

There were three treatment studies (de Oliveira 2001; Momeni 2009; Wigger-Alberti 2009) involving 124 people.

 
(3) Silicone gel sheeting compared with other silicone products

There was one prevention study (Niessen 1998) involving 129 people.
There were three treatment studies (Carney 1994; Karagoz 2009; Palmieri 1995) involving 152 people.

 
(4) Silicone gel sheeting compared with laser therapy

There were two treatment studies (Pacquet 2001; Wittenberg 1999) involving 40 people.

 
(5) Silicone gel sheeting compared with triamcinolone acetonide injection treatment

There were three treatment studies (Kelemen 2007; Sproat 1992; Tan 1999) involving 58 people.

 
(6) Silicone gel sheeting compared with topical onion extract

There was one treatment study (Karagoz 2009) involving 30 people.

 
(7) Silicone gel sheeting compared with pressure therapy

There was one treatment study (Li-Tsang 2010) involving 54 people.

There were many different measurement techniques and tools used, which made pooling of results difficult. The comparability of people at baseline was generally good, although one study (Pacquet 2001) provided no information on the control group, making it impossible to judge whether those groups were comparable. Most studies were also explicit about their inclusion and exclusion criteria, which allowed a clearer definition of the study population.

In most trials silicone gel sheeting was applied for at least 12 hours per day, with five studies (de Oliveira 2001; Li-Tsang 2006; Li-Tsang 2010; Momeni 2009; Niessen 1998) specifying 24 hours per day, another (Carney 1994) stating "as many hours per day as possible", and a third (Palmieri 1995) specifying 10 hours per day. However, two studies (Pacquet 2001; Wigger-Alberti 2009) did not indicate the number of hours that the silicone gel sheeting was worn by participants. One study (Niessen 1998) changed the type of silicone gel sheeting used (from Sil-K to Epiderm which is more adhesive) when the initial results from the first group of people (n = 80) were described by the authors as "disappointing". Another study (Carney 1994) also used two different types of gel (Silastic Gel Sheeting and Cica-Care) and analysed the treatment subgroups separately.

Descriptions and definitions of the type of scar (hypertrophic versus keloid) were adequate in 13 out of the 20 studies. Despite not giving a full description of the distinction between hypertrophic and keloid scars, de Oliveira 2001 classified their participants' scars as either one or the other, and separated the scar types in their analysis. Gold 2001 compared high-risk (i.e. those with a history of abnormal scarring) and low-risk participant groups in their results. Most other studies combined hypertrophic and keloid scars in their analyses, raising questions about the appropriateness of the study design (Shaffer 2002).

Given the long-term process of remodeling and scarring, it is recommended that follow-up continues for at least one year (Shaffer 2002). Only three studies (Carney 1994; Colom Majan 2006; Niessen 1998) had follow up of 12 months. Six studies (Ahn 1989; Gold 1994; Palmieri 1995; Sproat 1992; Tan 1999; Wigger-Alberti 2009) followed people for three months or less, which is clearly inadequate.

 

Risk of bias in included studies

The quality of trial methodology varied widely. The results for individual trials are presented in the 'Characteristics of included studies' table. Overall, the quality of the trial methodology in the included studies was poor. We judged only two studies (Momeni 2009; Wigger-Alberti 2009) to be at overall low risk of bias.

 

Allocation

 
Random sequence generation

Five studies (Colom Majan 2006; Li-Tsang 2010; Momeni 2009; Wigger-Alberti 2009; Wittenberg 1999) explicitly reported their method of generating the randomisation sequence and we judged them to be at low risk of selection bias. Colom Majan 2006, , Wigger-Alberti 2009 and Wittenberg 1999 used a computer-generated randomisation list; Sproat 1992 used a prescribed randomised sequence; Li-Tsang 2010 used the drawing of lots for randomisation; Momeni 2009 used a random number table. One study (Cruz-Korchin 1996) reported an inadequate method of randomisation and we judged this to be at high risk of selection bias. Cruz-Korchin 1996 allocated treatment based on the patient's dominant hand. The remainder did not describe their methods and we judged them at unclear risk of selection bias.

 
Allocation concealment

One study (Cruz-Korchin 1996) did not conceal allocation (they used the dominant or non dominant hand of the participant to decide where the material was placed) and we judged this to be at high risk of bias. The remaining studies did not report allocation concealment and were judged to be at unclear risk of bias.

 

Blinding

 
Blinding of participants and personnel

We judged two studies (Momeni 2009; Wigger-Alberti 2009) to have unclear risk of performance bias. One study (Momeni 2009) attempted to blind participants only by using placebo gel sheets on one- half of the scar but did not attempt to blind research personnel. The other study (Wigger-Alberti 2009) blinded research personnel by using an independent nurse to apply and remove all dressings in the investigators' absence. We judged the remaining studies to be at high risk of performance bias as they were unable to blind either participants or personnel due to the nature of the intervention.

 
Blinding of outcome assessor

We judged four studies (Li-Tsang 2006; Li-Tsang 2010; Momeni 2009; Sproat 1992) to have adequately blinded outcome assessors. Two studies (Li-Tsang 2006; Li-Tsang 2010) used an independent research assistant to judge the outcome; Momeni 2009 used an independent plastic surgeon; Sproat 1992 used photographs showed to five blinded observers and trained a 'blindfolded observer' to undertake measurements. We judged these four studies to be at low risk of detection bias. One study (Karagoz 2009) used the same outcome assessor at the beginning and end of the treatment and was not blinded. We judged this study was judged to be at high risk of detection bias. The remaining studies did not comment on blinding of outcome assessment and were judged to be at unclear risk of detection bias.

 

Incomplete outcome data

We judged fifteen15 studies (Ahn 1989; Colom Majan 2006; Cruz-Korchin 1996; Gold 1994; Karagoz 2009; Kelemen 2007; Li-Tsang 2006; Momeni 2009; Niessen 1998; Pacquet 2001; Palmieri 1995; Sproat 1992; Tan 1999; Wigger-Alberti 2009; Wittenberg 1999) to be at low risk of attrition bias. In each of these studies the numbers lost to follow up were low and adequate reasons were given for these losses. We judged the remaining studies to be at high risk of attrition bias. Three studies (Ahn 1991; Carney 1994; Gold 2001) had a loss to follow up greater than 20%. One study (Li-Tsang 2010) reported moderately high losses but was judged to be at high risk of bias because two thirds of drop outs came from the control group. One study (de Oliveira 2001) did not comment on attrition bias nor can it be ascertained from the data. We judged this study to be at unclear risk of attrition bias.

Clear statements of evidence of intention-to-treat (ITT) analysis were rarely presented in trial reports, and only two studies (Wigger-Alberti 2009; Wittenberg 1999) performed an ITT analysis.

 

Selective reporting

We judged one study (Kelemen 2007) to be at high risk of reporting bias, as only one "interesting" case from each group was reported, and patient ratings were not reported at all. We assessed all other studies in the review were assessed as having low risk of reporting bias. Although study protocols were not sought, all outcomes mentioned in the methods were reported in the results and clinically meaningful outcomes presented.

 

Other potential sources of bias

We judged seven studies (Ahn 1991; Colom Majan 2006; Gold 1994; Gold 2001; Li-Tsang 2006; Li-Tsang 2010; Wittenberg 1999) to be at high risk of bias due to the influence of companies supplying the silicone gel sheeting. Two studies (Ahn 1991; Gold 1994) reported receiving grant money from the companies supplying the silicone gel sheeting. Two studies (Colom Majan 2006; Gold 2001) stated that the research was supported by the company supplying the silicone gel but gave no further information. In the remaining three studies the company donated the silicone gel sheeting (Li-Tsang 2006; Li-Tsang 2010; Wittenberg 1999). The remaining studies appear free from other sources of bias.

 

Effects of interventions

Where available quantitative data are presented in the analysis tables.

 

How the results are presented and what the terms mean

Results of dichotomous variables are presented as risk ratio (RR) with 95% confidence intervals (CI). Risk ratio has been used rather than odds ratio as event rates are high in these trials and odd ratios would give an inflated impression of the magnitude of effect. Where statistically significant heterogeneity existed (i.e. the Chi² was greater than degrees of freedom) we used a random-effects model.

The types of outcomes measured in the studies are listed in the 'Characteristics of included studies' table. The primary outcome measure for prevention studies was the proportion of people who developed abnormal scarring in postoperative cases (measured in terms of blood flow, hyperpigmentation, erythema, thickness and regularity of scar). There were many different measurement techniques and tools used, making pooling of results difficult.

 

Comparison: silicone gel compared with no treatment

There were 13 studies (Ahn 1989; Ahn 1991; Carney 1994; Colom Majan 2006; Cruz-Korchin 1996; de Oliveira 2001; Gold 1994; Gold 2001; Li-Tsang 2006; Li-Tsang 2010; Niessen 1998; Tan 1999; Wittenberg 1999) in this category. Three of the studies (Cruz-Korchin 1996; Gold 2001; Niessen 1998) studied the prevention of scars for people undergoing surgery, eight studied the effect of silicone gel sheeting on existing hypertrophic or keloid scars (Ahn 1989; Carney 1994; Colom Majan 2006; de Oliveira 2001; Li-Tsang 2006; Li-Tsang 2010; Tan 1999; Wittenberg 1999) and two studies (Ahn 1991; Gold 1994) included both prevention and treatment.

 

I: Prevention studies

Of the five trials that compared silicone gel sheet with no treatment for prevention of scarring, four (Ahn 1991; Cruz-Korchin 1996; Gold 2001; Niessen 1998) included people with healed surgical wounds, and one (Gold 1994) included people who had had keloid scars removed with CO2 laser. Two of the trials described people according to their risk of developing abnormal scarring - Gold 1994 only recruited 'high-risk' people, while Gold 2001 recruited 'low' and 'high' risk people and presented the results of these two groups separately.

 
Primary outcome: development of keloid or hypertrophic scarring

Cruz-Korchin 1996 reported that fewer incisions treated with silicone gel sheeting became hypertrophic, though this difference was not significant(risk ratio (RR) 0.45, 95% confidence interval (CI) 0.19 to 1.07). Individually, two small trials (Gold 1994; Gold 2001) found no significant difference between the silicone gel sheeting and the control groups in terms of abnormal scarring in high-risk individuals only (people who were prone to scarring), but when pooled (random-effects) we found that silicone gel sheeting was associated with significantly fewer abnormal scars(RR 0.46, 95% CI 0.21 to 0.98). Ahn 1991 found significantly fewer abnormal scars in people treated with silicone gel sheeting (RR 0.05, 95% CI 0 to 0.76), whilst Niessen 1998 found a significant difference in favour of the control group(RR 2.71, 95% CI 1.19 to 6.22). When all five trials were pooled (random-effects, I² = 69%) there was no significant difference in the number of people developing abnormal scars (RR 0.55, 95% CI 0.21 to 1.45) ( Analysis 1.1). All these trials are susceptible to bias as they did not describe allocation concealment, blinding of outcome assessors or an intention-to-treat (ITT) analysis.

 
Secondary outcomes

Cruz-Korchin 1996 reported transient rash and minor skin maceration as complications, but there was no statistically significant difference between the groups. Niessen 1998 reported transient rash, which resolved on removal of the silicone gel sheeting. Pooling these studies (fixed-effect, I² = 0%) demonstrated a statistically significant difference in favour of the control groups. This means that more complications developed in the groups treated with silicone gel (RR 8.00, 95% CI 1.02 to 62.83) ( Analysis 1.2).

 

II: Treatment studies

Ten trials compared silicone gel sheeting with control for treating abnormal scarring (Ahn 1989; Ahn 1991; Carney 1994; Colom Majan 2006; de Oliveira 2001; Gold 1994; Li-Tsang 2006; Li-Tsang 2010; Tan 1999; Wittenberg 1999). The majority of control groups were untreated. In two studies the control group received lanolin and massage. Six trials included people with hypertrophic scars resulting from thermal burns (Carney 1994; Gold 1994; Li-Tsang 2006; Li-Tsang 2010) or surgery (Colom Majan 2006; Wittenberg 1999). Three (Ahn 1991; Ahn 1989; de Oliveira 2001) included people with hypertrophic and keloid scarring, and one (Tan 1999) only included people with keloid scarring.

 
Primary outcome

As the studies used different outcome measures it was impossible to pool results. We examined outcomes of reduction of scar length and width (de Oliveira 2001), scar thickness (Li-Tsang 2006; Li-Tsang 2010) and reduction in scar size by 50% (Tan 1999). The studies found no significant difference between silicone gel sheeting and control for reduction in scar length, width and reduction of size by 50% ( Analysis 1.3;  Analysis 1.4;  Analysis 1.7) but significant results for scar thickness favouring silicone gel (RR -2.00, 95% CI -2.14 to -1.85) ( Analysis 1.5) although this was only two studies (Li-Tsang 2006; Li-Tsang 2010) with relatively small numbers (N = 77).

 
Secondary outcomes

All studies except Wittenberg reported secondary outcomes. There were no statistically significant differences between the treatment or control groups for improvements in scar appearance, scar colour and the relief of itching and pain.

Five studies (Colom Majan 2006; de Oliveira 2001; Li-Tsang 2006; Tan 1999de Oliveira 2001Li-Tsang 2010; Tan 1999) showed a statistically significant amelioration of scar colour (defined as a significant improvement in erythema) with silicone gel (pooled RR 3.49, 95% CI 1.97 to 6.15, fixed-effect, I² = 53%) ( Analysis 1.8). When a random-effects model is applied this result is still statistically significant. It should be noted, however, that with the exception of Li-Tsang 2010 who used spectrocolorimetry, this is a subjective outcome and only two studies (de Oliveira 2001; Li-Tsang 2010) masked the outcome assessor. Also, only Li-Tsang 2010 reported the method of randomisation and no studies had adequate allocation concealment.

Four studies (Ahn 1989; Ahn 1991; Carney 1994; Li-Tsang 2006) reported a statistically significant improvement in scar elasticity in those people treated with silicone gel sheeting. Data were presented graphically (mean percentage of stretch and standard error of mean in Ahn 1989 and Ahn 1991; percentage of extensibility of scar in Carney 1994; mean only in Li-Tsang 2006) with P values, but actual measurement data were not reported. We requested further information from trial authors, with two replies (Li-Tsang 2006; Li-Tsang 2010) resulting in new data. We treated reported data as dichotomous (i.e. improvement in elasticity compared with no improvement) and due to the high heterogeneity likely caused by the different measurement methods (I² = 55%), pooled using a random-effects model resulting in a statistically significant improvement in scar elasticity (RR 3.03, 95% CI 1.02 to 8.99) ( Analysis 1.9).

Results for relief of pain and itch (Li-Tsang 2006; Li-Tsang 2010; Tan 1999) showed no statistically significant difference between the groups ( Analysis 1.10).

Three studies (Ahn 1989; Carney 1994; Colom Majan 2006) reported complications such as transient skin rashes, pruritis, itching or superficial maceration. Authors reported that these resolved promptly when the silicone gel sheeting was withdrawn, or when correct hygiene was practised. Combining results from Ahn 1989 and Colom Majan 2006 we found statistically significantly more complications reported for silicone gel sheeting than in the control group (RR 9.52, 95% CI 1.35 to 67.10, fixed-effect, I² = 0%) ( Analysis 1.11). No raw data were reported by Carney and email communication with the author did not produce further data.

 

Comparison: silicone gel compared with non silicone dressing

 

I: Prevention studies

No prevention studies were identified.

 

II: Treatment studies

Three studies (de Oliveira 2001; Momeni 2009; Wigger-Alberti 2009) including 124 people compared silicone gel sheeting with non silicone gel sheeting. One study (de Oliveira 2001) classified scars as either hypertrophic or keloid, and the other two only included hypertrophic scars.

 
Primary outcome

There was no statistically significant difference between the two groups for reduction of scar width or scar length ( Analysis 2.1;  Analysis 2.2).

 
Secondary outcomes

There was no statistically significant difference between the two groups for amelioration of scar colour (RR 1.01, 95% CI 0.87 to 1.17) ( Analysis 2.3).
Two studies reported complications. de Oliveira 2001 reported irritative contact dermatitis which was resolved by washing the skin and removing the silicone gel sheeting for five hours. Wigger-Alberti 2009 reported two adverse events described as local dermatitis which occurred in the silicone gel group. The final study (Momeni 2009) reported no adverse events in either group.

 

Comparison: silicone gel sheeting compared with silicone gel sheeting with different contact layers

 

I: Prevention studies

One study (Niessen 1998) involved 155 women undergoing bilateral breast reduction. This trial had three arms and scars were either treated with adhesive silicone gel sheeting (Epiderm adhesive), non adhesive silicone gel sheeting (Sil-K) or covered with Micropore alone.

 
Primary outcome

The authors reported that 12 months after surgery no difference in hypertrophic scar development was found between the adhesive and non adhesive silicone gel sheets. However, they did not present separate data for the two intervention groups, but reported combined data for the silicone gel sheeting groups (adhesive plus non adhesive) compared with the control group. This trial was poorly reported and the method of allocating treatment to scar site was unclear. There was no blinded outcome assessment and no ITT analysis.

 
Secondary outcomes

Results obtained from the trial author (Niessen) by email on 238 scars (114 adhesive silicone gel group, 124 non adhesive silicone gel group) showed no statistically significant difference in results for scar width, height, colour and perfusion at 12 months post surgery ( Analysis 6.1;  Analysis 6.2;  Analysis 6.3;  Analysis 6.4).

 

II: Treatment studies

Three studies were included in this category. One (Palmieri 1995) compared silicone gel sheets to silicone gel sheets with added vitamin E. This study involved 80 people with established hypertrophic and keloid scars resulting from either surgery or thermal burns. One (Karagoz 2009) compared silicone gel sheets to a paint-on silicone gel and included a total of 30 people with hypertrophic scarring post-thermal burns in this part of the study. The third study (Carney 1994) compared adhesive (Cica-Care) with non adhesive (Silastic) silicone gel sheeting, and included 42 people with 47 hypertrophic scars.

 
Primary outcome

Palmieri 1995 reports that photographs of scar size, colour and cosmesis were objectively scored on a scale of zero to five, however these results appear to have been combined with patient self ratings of itching and pain on a Scott-Huskisson scale. We contacted the authors for clarification, but they did not reply, therefore these data could not be used and it was impossible to draw conclusions about the effectiveness of either treatment for change in scar size, or determine whether the assessors were blinded to treatment allocation. Size of scar was not measured by Carney 1994 or Karagoz 2009.

 
Secondary outcomes

Carney 1994 did not provide a statistical analysis of the comparison between the two silicone gel sheets, but stated that after six months of treatment, 88.9% of scars in the non adhesive gel group, and 100% of the scars in the adhesive group were improved for colour, and 100% of both groups were improved for scar softness. We contacted the lead author and asked them for data, however the author replied that the actual data had not been retained.

Palmieri 1995 reported a combined subjective and objective score, which showed that 75% of people treated with silicone gel sheeting had improvements in cosmesis, pain and itching of at least 50%, compared with 90% of those treated with silicone gel plates with added vitamin E. There was a statistically significant improvement in favour of silicone gel sheet with added vitamin E (RR 0.79, 95% CI 0.65 to 0.96) ( Analysis 3.5). No complications were reported.

Karagoz 2009 used the Vancouver Scar Scale, reporting mean total scores and sub-scale scores before and after treatment. They concluded that there was no significant difference between the silicone gel sheets and the paint-on silicone group. Patient ratings of improvement on a four-point scale were presented, but no statistical analysis was undertaken.

Given the presentation of results in these studies, it is impossible to draw a conclusion regarding the effectiveness of either treatment for the primary outcome (change in scar size).

 

Comparison: silicone gel sheeting compared with laser therapy

 

I: Prevention studies

No prevention studies were identified.

 

II: Treatment studies

Two studies (Pacquet 2001; Wittenberg 1999) involving 40 people compared the use of silicone gel sheeting with 585 nm pulsed dye laser therapy.

 
Primary outcome

Although scar size was measured in both studies, Pacquet 2001 did not report results at all and Wittenberg 1999 presented results for volume in graphical form only. We contacted both, but no responses were received.

 
Secondary outcomes

Pacquet 2001 found no statistically significant difference in scar erythema between people receiving silicone gel sheeting compared with those receiving 585 nm pulsed dye laser therapy. Similarly, Wittenberg 1999 also found no statistically significant difference in pain or burning, scar elasticity or fibrosis in people receiving these treatments. Since the published results in both papers were presented graphically and specific numerical data were not provided, no analyses tables or graphs are available in this review. No complications were reported by Pacquet 2001, although Wittenberg 1999 reported that one patient withdrew because of pain on laser treatment, and one patient was unable to use the silicone gel sheeting because of skin irritation.

 

Comparison: silicone gel sheeting compared with triamcinolone acetonide injection treatment

 

I: Prevention studies

No prevention studies were identified.

 

II: Treatment studies

Three studies involving 58 people were identified (Kelemen 2007; Sproat 1992; Tan 1999). Triamcinolone acetonide injections are an existing treatment for hypertrophic scars but can be painful.

 
Primary outcome

Tan 1999 reported that two out of the 17 people (12%) treated with silicone gel sheeting had a statistically significant reduction (defined as at least 50%) in the size of keloid scars, in contrast to the 16 out of 17 people (94%) who had a significant reduction when treated with intralesional injections of triamcinolone acetonide (40 mg/ml). The RR was 0.13 (95% CI 0.03 to 0.46) ( Analysis 4.1). Sproat 1992 reported changes in scar height and width graphically. We contacted the researcher, but they had not kept specific numerical data, so no analyses tables or graphs are available in this review for these measures. Sproat 1992 reported that scar height decreased for both treatment groups, but that scar width increased in both (more so with triamcinolone acetonide injection). This trial report was not supported by any data analysis and therefore must be viewed with caution. Kelemen 2007 concluded that the intralesional steroid injection group had greater improvement of Vancouver scale scores after eight weeks than the silicone group, however they also did not provide any data analysis, so again these conclusions must be viewed with caution.

 
Secondary outcomes

Tan 1999 reported that people treated with the injections showed a statistically significant improvement in erythema compared to those treated with silicone gel sheeting; the RR was 0.10 (95% CI 0.01 to 0.70) ( Analysis 4.2). There was no statistically significant difference for symptomatic relief of itching and pain ( Analysis 4.3). Sproat 1992 reported a statistically significant difference in mean time to symptomatic improvement (mean difference -2.90 days, 95% CI -3.93 to -1.87) ( Analysis 4.4) and patient preference in favour of the silicone gel sheeting (RR 5.50, 95% CI 1.48 to 20.42) ( Analysis 4.5). Kelemen 2007 reported a faster reduction in patient-reported symptoms (measured on a Likert scale), but provided no data to support this claim.

Sproat 1992 reported that statistically significantly more participants in the triamcinolone injection group experienced complications (including severe pain (71% of people), skin atrophy, pigmentary changes and white bead-like skin deposits (64% of people)) compared with one instance of superficial rash in the silicone gel sheeting group (which resolved on discontinuation of the sheeting for two days) (RR 0.10, 95% CI 0.01 to 0.68) ( Analysis 4.6). Tan 1999 and Kelemen 2007 both reported that no adverse reactions occurred with either treatment.

 

Comparison: silicone gel sheeting compared with topical onion extract

 

I: Prevention studies

No prevention studies were identified.

 

II: Treatment studies

One study involving 30 people was identified (Karagoz 2009).

 
Primary outcome

This study used spectrocolorimeter and Tissue Ultrasound Palpation System (TUPS) to measure scar colour and thickness respectively. The Vancouver Scar Scale was used to measure scar pliability. All scores were reported as mean/standard deviation (SD) of total scores for each group. After six months of intervention, there was a significant difference between the total score for the silicone gel sheeting and topical onion extract groups in favour of the silicone gel sheeting group (MD 1.90, 95%CI 0.62 to 3.18  Analysis 5.1). Patient ratings of improvement on a four-point scale were presented, but no statistical analysis was undertaken.

Two participants in the silicone gel sheeting group developed skin maceration and pruritis, but this resolved after interrupting treatment for a week.

 

Comparison: silicone gel sheeting compared with pressure therapy

 

I: Prevention studies

No prevention studies were identified.

 

II: Treatment studies

One study involving 54 people was identified (Li-Tsang 2010).

 
Primary outcome

This study used a spectrocolorimeter to measure colour (lightness, redness and yellowness), Tissue Ultrasound Palpation System (TUPS) to measure thickness and the Vancouver Scar Scale to measure pliability. Pain and itch were measured using a 10-point visual analogue scale. Means and SDs were reported for all measures up to six months post commencement of treatment. No significant differences were found between the pressure therapy and the silicone gel sheeting groups on measures of scar thickness, scar colour lightness and yellowness, or pliability ( Analysis 6.1;  Analysis 6.2). Pain and itch were both significantly lower in the silicone gel sheeting group ( Analysis 6.3;  Analysis 6.4).

No complications were reported in either group.

 

Discussion

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

The introduction of silicone gel sheeting as both a prevention and treatment intervention in the early 1980s has led to a number of research trials of varied quality.

Whilst there is some weak evidence from two small trials (total 51 participants - see comparison 1.1.1 in  Analysis 1.1) that silicone gel-treated incisions are less likely to become hypertrophic in high-risk people, these trials had a high potential for selection and detection bias (method of randomisation unclear; no blinding of outcome assessors) and therefore must be viewed with a great deal of caution.

Similarly the findings that silicone gel sheeting improves the elasticity and colour of keloid scars came from low-quality studies. Whilst triamcinolone appeared more effective at improving keloid scarring than silicone gel sheeting this finding too was from a single study with high susceptibility to bias (unclear randomisation; lack of blinding of outcome assessors).

Complications of silicone gel sheeting use including itch and skin rashes were reported in three trials and were more common than in control groups.

In this review, only randomised controlled trials (RCTs), quasi-RCTs (QRCTs) and controlled clinical trials (CCTs) were considered, leading to a relatively small number of studies (20) and people (873) for evaluation. Few studies compared similar interventions or measured similar criteria. Several trials had methodological problems, and reported inadequately on their randomisation protocols and/or allocation concealment, or failed to undertake an intention-to-treat analysis. Blinding of outcome assessors, which would not have been difficult to achieve, was poorly reported. None of the included trials addressed health-related quality of life, the minimum meaningful difference in scar characteristics such as size or colour, or the cost of treatments. In addition there is the potential for unit of analysis errors, some trials used the person as the unit of analysis, others the scar and in some cases the person was used as their own control, multiple scars on one person treated as being independent in the analysis would inflate precision of any pooled estimates, in general the reporting in this area was poor.

There was also some inconsistency in instruments of measurement, for example, different patient rating scales for pain/irritation/itch were used, making it difficult to compare results.

All but three of the studies had short duration of follow-up (i.e. less than 12 months), which is inadequate given that scar remodeling and collagen synthesis continues for over a year.

It is interesting to note the difference between the results from the Niessen 1998 and Cruz-Korchin 1996 trials when their clinical experiments were so similar (both treated women who had recently undergone breast reductions). Both researchers defined the difference in their trials, via letters published in Annals of Plastic Surgery (1997), in an attempt to explain their results. Niessen stated that the most important difference was the application of Micropore (3M) which provided support around the control (untreated) scars, thus demonstrating that "...it is not the silicone material itself that prevents the development of hypertrophic scar tissue". In her response, Cruz-Korchin 1997 agreed that support would tend to reduce scar width, but silicone sheets would reduce width and flatten the hypertrophic scar. She also observed that her study population was composed mainly of Hispanics who are more prone to forming hypertrophic scars, and compared this to Niessen's study population of "fair-skinned Caucasians, in whom hypertrophic scarring seldom occurs". At present this trial is the only one to have compared Micropore against silicone gel sheeting and, therefore, more research is needed to investigate whether the physical support of the scar is as effective as silicone gel sheeting.

In summary the effects of silicone gel sheeting on hypertrophic and keloid scarring are unclear and warrant rigorous evaluation.

 

Authors' conclusions

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

 

Implications for practice

The main aims for practitioners dealing with wound healing and scar minimisation are good skin closure, elasticity, maintenance of functioning of underlying structures and good cosmetic appearance. There are many treatments available to prevent or minimise scarring (including, but not limited to, pressure therapy, topical moisturisers, surgical excision, intralesional corticosteroids, laser therapy, cryotherapy, silicone or non silicone gel sheeting) but these vary in how well they are tolerated, as some people find them painful, uncomfortable and/or expensive. Practitioners need to match treatments to the needs and wishes of their patients.

In this review, the evidence for the effects of silicone gel sheeting on scarring are obscured by the poor quality of the research. Thus, whilst there appeared to be fewer abnormal scars in people at high risk of developing hypertrophic or keloid scars, and improved scar colour and softness in existing scars treated with silicone gel sheeting, these findings are highly susceptible to bias. The increased incidence of adverse effects with silicone gel sheeting must also be taken in to account.

 
Implications for research

Given the functional and psychological impact of hypertrophic and keloid scarring, it is surprising that there are so few high-quality research trials investigating the preventative and treating qualities of silicone gel sheeting. Such information would be welcomed by practitioners, together with estimates of benefit and complication rates.

Robust research to clarify the issues discussed in this review would consist of a trial that incorporated the following criteria:

  1. blinded allocation and outcome assessment;
  2. standardised, objective, validated and repeatable outcome measurement;
  3. adequate duration of follow-up (at least 12 months, but preferably 18 months);
  4. collection and reporting of recurrence data;
  5. distinction between type of scar (hypertrophic versus keloid) and separation of results by scar type in the analysis.

A detailed list of suggestions for future research in keloid scar treatment is included in Shaffer 2002.

 

Acknowledgements

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

The authors would like to thank Anita Kainth, Michael Bigby and the Cochrane Wounds Group Editors (Nicky Cullum, David Margolis and Andrea Nelson) who refereed the protocol and review, June Poston who initiated the review, Jesus Lopez Alcalde, Arturo Marti-Carvajal and Emese Mayhew, who provided translation assistance and Jenny Bellorini for copy editing the review. In addition, the authors would like to thank the staff at the Australasian Cochrane Centre who have been of enormous assistance, Dr Bess Fowler (formerly of Curtin University, School of Occupational Therapy) for support, encouragement and guidance and the staff of the Cochrane Wounds Group. Abhay Pandit performed previous work that was the foundation of the current review but did not contribute to the updating process, similarly Sally Stapley contributed to the first update but not to the original review nor the current update, we acknowledge their contributions.

 

Data and analyses

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms
Download statistical data

 
Comparison 1. Silicone gel versus no treatment (control)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Development of abnormal scarring - prevention5402Risk Ratio (M-H, Random, 95% CI)0.55 [0.21, 1.45]

    1.1 High risk of scarring
251Risk Ratio (M-H, Random, 95% CI)0.46 [0.21, 0.98]

    1.2 Low risk of scarring
131Risk Ratio (M-H, Random, 95% CI)0.35 [0.02, 8.08]

    1.3 Risk not stated
3320Risk Ratio (M-H, Random, 95% CI)0.57 [0.10, 3.40]

 2 Development of complications - prevention2350Risk Ratio (M-H, Fixed, 95% CI)8.0 [1.02, 62.83]

    2.1 Prevention
2350Risk Ratio (M-H, Fixed, 95% CI)8.0 [1.02, 62.83]

 3 Reduction of scar length - treatment127Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 4 Reduction in scar width - treatment127Mean Difference (IV, Fixed, 95% CI)0.0 [0.0, 0.0]

 5 Scar thickness - treatment277Mean Difference (IV, Fixed, 95% CI)0.00 [-2.14, -1.85]

 6 Scar pliability - treatment268Mean Difference (IV, Fixed, 95% CI)-0.74 [-0.83, -0.64]

 7 Reduction of keloid scar size by 50% - treatment134Risk Ratio (M-H, Fixed, 95% CI)5.0 [0.26, 97.00]

 8 Scar colour amelioration - treatment5151Risk Ratio (M-H, Fixed, 95% CI)3.49 [1.97, 6.15]

 9 Improvement in scar elasticity - treatment5154Risk Ratio (M-H, Random, 95% CI)3.03 [1.02, 8.99]

 10 Symptomatic relief of itching and pain - treatment397Risk Ratio (M-H, Random, 95% CI)1.23 [0.78, 1.96]

 11 Development of complications - treatment239Risk Ratio (M-H, Fixed, 95% CI)9.52 [1.35, 67.10]

 
Comparison 2. Silicone gel versus non silicone dressing

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Reduction of scar width130Mean Difference (IV, Fixed, 95% CI)-0.03 [-0.15, 0.09]

 2 Reduction of scar length130Mean Difference (IV, Fixed, 95% CI)-0.02 [-0.07, 0.03]

 3 Scar colour improvement2136Risk Ratio (M-H, Fixed, 95% CI)1.01 [0.87, 1.17]

 
Comparison 3. Silicone gel versus silicone gel with different contact layers

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Scar width - prevention1238Mean Difference (IV, Fixed, 95% CI)0.80 [-0.01, 1.61]

 2 Scar height - prevention1238Mean Difference (IV, Fixed, 95% CI)0.0 [-0.10, 0.10]

 3 Scar colour - prevention1233Mean Difference (IV, Fixed, 95% CI)-0.20 [-0.78, 0.38]

 4 Scar perfusion - prevention1235Mean Difference (IV, Fixed, 95% CI)-1.40 [-4.25, 1.45]

 5 Improvement >50% in cosmesis, itching and pain - treatment180Risk Ratio (M-H, Fixed, 95% CI)0.79 [0.65, 0.96]

 
Comparison 4. Silicone gel versus triamcinolone acetonide injection treatment

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Reduction of keloid scar size by 50%134Risk Ratio (M-H, Fixed, 95% CI)0.13 [0.03, 0.46]

 2 Improvement in erythema134Risk Ratio (M-H, Fixed, 95% CI)0.1 [0.01, 0.70]

 3 Symptomatic relief of itching and pain118Risk Ratio (M-H, Fixed, 95% CI)0.6 [0.20, 1.79]

 4 Average time (in days) to improvement128Mean Difference (IV, Fixed, 95% CI)-2.9 [-3.93, -1.87]

 5 Patient preference128Risk Ratio (M-H, Fixed, 95% CI)5.5 [1.48, 20.42]

 6 Development of complications128Risk Ratio (M-H, Fixed, 95% CI)0.1 [0.01, 0.68]

 
Comparison 5. Silicone gel versus topical onion extract

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Improvement in Vancouver Scar Scale130Mean Difference (IV, Fixed, 95% CI)1.90 [0.62, 3.18]

 
Comparison 6. Silicone gel versus pressure therapy

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Scar thickness - treatment148Mean Difference (IV, Fixed, 95% CI)-0.24 [-0.97, 0.49]

 2 Scar pliability - treatment148Mean Difference (IV, Fixed, 95% CI)-0.35 [-0.85, 0.15]

 3 Pain148Mean Difference (IV, Fixed, 95% CI)-1.90 [-2.99, -0.81]

 4 Itching144Mean Difference (IV, Fixed, 95% CI)-2.04 [-3.16, -0.92]

 

Appendices

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms
 

Appendix 1. Search strategy for the first review update 2008

 

Electronic searches

For this first update the following databases were searched:

  • The Cochrane Wounds Group Specialised Register (searched 21/11/07);
  • The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library Issue 4, 2007
  • Ovid MEDLINE (2005 to November Week 1 2007)
  • Ovid EMBASE (2005 to 2007 Week 46)
  • Ovid CINAHL (2005 to November Week 3 2007)

The following search strategy was used to search CENTRAL:
1 MeSH descriptor Keloid explode all trees
2 MeSH descriptor Cicatrix, Hypertrophic explode all trees
3 MeSH descriptor Hypertrophy explode all trees
4 keloid* or hypertrophic or cicatrix
5 scar or scars or scarred or scarring
6 (#1 OR #2 OR #3 OR #4 OR #5)
7 MeSH descriptor Silicone Gels explode all trees
8 silicone NEXT gel*
9 silicone NEXT sheet*
10 silicone NEXT dressing*
11 (#7 OR #8 OR #9 OR #10)
12 (#6 AND #11)

The following search strategy was used in MEDLINE and was modified as necessary for EMBASE and CINAHL (available upon request).
1 exp Keloid/
2 exp Cicatrix, Hypertrophic/
3 exp Hypertrophy/
4 (keloid$ or hypertrophic or cicatrix).mp.
5 (scar or scars or scarred or scarring).mp.
6 or/1-5
7 exp Silicone Gels/
8 (silicone adj gel$).mp.
9 (silicone adj sheet$).mp.
10 (silicone adj dressing$).mp.
11 or/7-10
12 6 and 11

The MEDLINE search was combined with the Cochrane highly sensitive search strategy for identifying reports of randomised controlled trials. The EMBASE and CINAHL searches were combined with the trial filters developed by the Scottish Intercollegiate Guidelines Network (Highly sensitive search strategies for identifying reports of randomised controlled trials in MEDLINE.

 

Searching other resources

The reference lists of relevant review articles and all included studies were examined to identify further studies. The major supplier of silicon gel sheeting (Smith and Nephew) was approached for details of unpublished, ongoing and recently published trials. The search was not limited by language or publication status.

 

Appendix 2. Medline, Embase and CINAHL search strategies

Medline

1 exp Keloid/ (1408)
2 exp Cicatrix, Hypertrophic/ (1151)
3 exp Hypertrophy/ (25586)
4 (keloid* or hypertrophic or cicatrix).tw. (17938)
5 (scar or scars or scarred or scarring).tw. (29856)
6 or/1-5 (67405)
7 exp Silicone Gels/ (728)
8 (silicon* adj gel*).tw. (576)
9 (silicon* adj sheet*).tw. (165)
10 (silicon* adj dressing*).tw. (33)
11 or/7-10 (1212)
12 6 and 11 (210)
13 randomized controlled trial.pt. (247106)
14 controlled clinical trial.pt. (40090)
15 randomized.ab. (201489)
16 placebo.ab. (93457)
17 clinical trials as topic.sh. (80864)
18 randomly.ab. (138656)
19 trial.ti. (75110)
20 or/13-19 (557914)
21 (animals not (humans and animals)).sh. (1647357)
22 20 not 21 (507505)
23 12 and 22 (43)

Embase

1 exp Scar/ (32741)
2 (keloid* or hypertrophic or cicatrix).tw. (25878)
3 (scar or scars or scarred or scarring).tw. (45069)
4 or/1-3 (76936)
5 exp Silicone Gel/ (793)
6 (silicon* adj gel*).tw. (776)
7 (silicon* adj sheet*).tw. (229)
8 (silicon* adj dressing*).tw. (50)
9 or/5-8 (1475)
10 4 and 9 (389)
11 exp Clinical trial/ (802169)
12 Randomized controlled trial/ (290844)
13 Randomization/ (51197)
14 Single blind procedure/ (15897)
15 Double blind procedure/ (87219)
16 Crossover procedure/ (32445)
17 Placebo/ (169756)
18 Randomi?ed controlled trial$.tw. (82914)
19 RCT.tw. (10982)
20 Random allocation.tw. (931)
21 Randomly allocated.tw. (14603)
22 Allocated randomly.tw. (1227)
23 (allocated adj2 random).tw. (266)
24 Single blind$.tw. (9897)
25 Double blind$.tw. (92147)
26 ((treble or triple) adj blind$).tw. (248)
27 Placebo$.tw. (140349)
28 Prospective study/ (206934)
29 or/11-28 (1107742)
30 Case study/ (16788)
31 Case report.tw. (170882)
32 Abstract report/ or letter/ (519805)
33 or/30-32 (703087)
34 29 not 33 (1079210)
35 animal/ (730814)
36 human/ (8821758)
37 35 not 36 (489053)
38 34 not 37 (1056645)
39 10 and 38 (96)

CINAHL

S9 S5 and S8
S8 S6 or S7
S7 TI ( silicon* gel* or silicon* sheet* or silicon* dressing* ) or AB ( silicon* gel* or silicon* sheet* or silicon* dressing* )
S6 (MH "Silicones")
S5 S1 or S2 or S3 or S4
S4 TI ( scar or scars or scarred or scarring ) or AB ( scar or scars or scarred or scarring )
S3 TI ( keloid* or hypertrophic or cicatrix ) or AB ( keloid* or hypertrophic or cicatrix )
S2 (MH "Cicatrix+")
S1 (MH "Keloid")

 

Appendix 3. Risk of bias criteria

 

1.  Was the allocation sequence randomly generated?

 
Low risk of bias

The investigators describe a random component in the sequence generation process such as: referring to a random number table; using a computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots.

 
High risk of bias

The investigators describe a non-random component in the sequence generation process. Usually, the description would involve some systematic, non-random approach, for example: sequence generated by odd or even date of birth; sequence generated by some rule based on date (or day) of admission; sequence generated by some rule based on hospital or clinic record number.

 
Unclear

Insufficient information about the sequence generation process to permit judgement of low or high risk of bias.

 

2.  Was the treatment allocation adequately concealed?

 
Low risk of bias

Participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomisation); sequentially-numbered drug containers of identical appearance; sequentially-numbered, opaque, sealed envelopes.

 
High risk of bias

Participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: using an open random allocation schedule (e.g. a list of random numbers); assignment envelopes were used without appropriate safeguards (e.g. if envelopes were unsealed or non opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.

 
Unclear

Insufficient information to permit judgement of low or high risk of bias. This is usually the case if the method of concealment is not described or not described in sufficient detail to allow a definite judgement, for example if the use of assignment envelopes is described, but it remains unclear whether envelopes were sequentially numbered, opaque and sealed.

 

3.  Blinding - was knowledge of the allocated interventions adequately prevented during the study?

 
Low risk of bias

Any one of the following.

  • No blinding, but the review authors judge that the outcome and the outcome measurement are not likely to be influenced by lack of blinding.
  • Blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.
  • Either participants or some key study personnel were not blinded, but outcome assessment was blinded and the non-blinding of others unlikely to introduce bias.

 
High risk of bias

Any one of the following.

  • No blinding or incomplete blinding, and the outcome or outcome measurement is likely to be influenced by lack of blinding.
  • Blinding of key study participants and personnel attempted, but likely that the blinding could have been broken.
  • Either participants or some key study personnel were not blinded, and the non-blinding of others likely to introduce bias.

 
Unclear

Any one of the following.

  • Insufficient information to permit judgement of low or high risk of bias.
  • The study did not address this outcome.

 

4. Were incomplete outcome data adequately addressed?

 
Low risk of bias

Any one of the following.

  • No missing outcome data.
  • Reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias).
  • Missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups.
  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk not enough to have a clinically relevant impact on the intervention effect estimate.
  • For continuous outcome data, plausible effect size (difference in means or standardised difference in means) among missing outcomes not enough to have a clinically relevant impact on observed effect size.
  • Missing data have been imputed using appropriate methods.

 
High risk of bias

Any one of the following.

  • Reason for missing outcome data likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups.
  • For dichotomous outcome data, the proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate.
  • For continuous outcome data, plausible effect size (difference in means or standardised difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size.
  • ‘As-treated’ analysis done with substantial departure of the intervention received from that assigned at randomisation.
  • Potentially inappropriate application of simple imputation.

 
Unclear

Any one of the following.

  • Insufficient reporting of attrition/exclusions to permit judgement of low or high risk of bias (e.g. number randomised not stated, no reasons for missing data provided).
  • The study did not address this outcome.

 

5. Are reports of the study free of suggestion of selective outcome reporting?

 
Low risk of bias

Any of the following.

  • The study protocol is available and all of the study’s pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way.
  • The study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified (convincing text of this nature may be uncommon)

 
High risk of bias

Any one of the following.

  • Not all of the study’s pre-specified primary outcomes have been reported.
  • One or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre-specified.
  • One or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect).
  • One or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis.
  • The study report fails to include results for a key outcome that would be expected to have been reported for such a study.

 
Unclear

Insufficient information to permit judgement of low or high risk of bias. It is likely that the majority of studies will fall into this category.

 

6. Other sources of potential bias

 
Low risk of bias

The study appears to be free of other sources of bias.

 
High risk of bias

There is at least one important risk of bias. For example, the study:

  • had a potential source of bias related to the specific study design used; or
  • has been claimed to have been fraudulent; or
  • had some other problem.

 
Unclear

There may be a risk of bias, but there is either:

  • insufficient information to assess whether an important risk of bias exists; or
  • insufficient rationale or evidence that an identified problem will introduce bias.

 

What's new

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

Last assessed as up-to-date: 8 May 2013.


DateEventDescription

8 May 2013New citation required but conclusions have not changedFive new studies were included (Karagoz 2009; Kelemen 2007; Li-Tsang 2010; Momeni 2009; Wigger-Alberti 2009). Seven studies were excluded and we requested additional data from three authors (responses from two were received at the time of writing). The review authors’ conclusions remain unchanged.

8 May 2013New search has been performedSecond update, new searches.



 

History

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

Protocol first published: Issue 3, 2002
Review first published: Issue 1, 2006


DateEventDescription

23 May 2008AmendedConverted to new review format.

11 February 2008New search has been performedFor this first update, new searches were carried out in January and November 2007. Two new studies were included (Colom Majan 2006; Li-Tsang 2006). Seven studies were excluded and we requested additional data from a further two (this has not been received at the time of writing). The review authors' conclusions remain unchanged.

15 November 2005New citation required and conclusions have changedSubstantive amendment



 

Contributions of authors

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

Lisa O'Brien co-ordinated the review update, extracted data and checked the quality of data extraction, analysed or interpreted data, checked quality assessment, made an intellectual contribution to the review and wrote to study authors/experts/companies.
Danny Jones extracted data, undertook quality assessment, analysed or interpreted data, completed the first draft of the review update, performed part of the writing or editing of the review update, made an intellectual contribution to the review update, approved the final review update prior to submission.

 

Contributions of editorial base:

Nicky Cullum: edited the review, advised on methodology, interpretation and review content. Approved the final review and first review update prior to submission.
Andrea Nelson, Editor: edited the second review update, advised on methodology and approved the second review update prior to submission.
Sally Bell-Syer: coordinated the editorial process. Advised on methodology, interpretation and content. Edited the review and the updates of the review.
Ruth Foxlee: designed the search strategy, ran the searches and edited the search methods section for the updates.

 

Declarations of interest

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms

None known.

 

Sources of support

  1. Top of page
  2. Background
  3. Objectives
  4. Methods
  5. Results
  6. Discussion
  7. Authors' conclusions
  8. Acknowledgements
  9. Data and analyses
  10. Appendices
  11. What's new
  12. History
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Index terms
 

Internal sources

  • No sources of support supplied

 

External sources

  • Australasian Cochrane Centre, Australia.
  • School of Occupational Therapy, Curtin University, Australia.
  • NIHR/Department of Health (England), (Cochrane Wounds Group), UK.

* Indicates the major publication for the study

References

References to studies included in this review

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. Additional references
Ahn 1989 {published data only}
  • Ahn ST, Monafo WW, Mustoe TA. Topical silicone gel: a new treatment for hypertrophic scars. Surgery 1989;106(4):781-6; discussion 786-7.
Ahn 1991 {published data only}
  • Ahn ST, Monafo WW, Mustoe TA. Topical silicone gel for the prevention and treatment of hypertrophic scar. Archives of Surgery 1991;126(4):499-504.
Carney 1994 {published data only}
Colom Majan 2006 {published data only}
  • Colom Majan JI. Evaluation of a self-adherent soft silicone dressing for the treatment of hypertrophic postoperative scars: negative pressure wound therapy to treat hematomas and surgical incisions following high-energy trauma. Journal of Wound Care 2006;15(5):193-6.
  • Colom Maján JI. Treatment with a self-adherent soft silicone gel dressing versus no treatment on postoperative scars. 12th Conference of the European Wound Management Association; 2002, 23-25 May; Granada, Spain. 2002:336.
Cruz-Korchin 1996 {published data only}
de Oliveira 2001 {published data only}
Gold 1994 {published data only}
  • Gold M. Topical silicone gel sheeting - 1999 update. 9th European Conference on Advances in Wound Management; 1999, 9-11 November; Harrogate UK. 1999:21, Poster No.1.
  • Gold MH. A controlled clinical trial of topical silicone gel sheeting in the treatment of hypertrophic scars and keloids. Journal of the American Academy of Dermatology 1994;30(3):506-7.
Gold 2001 {published data only}
  • Gold M. The prevention of hypertrophic scars and keloids by the prophylactic use of topical silicone gel sheets following a surgical procedure. 20th World Congress of Dermatology; 2002, 1-5 July; Paris. 2002:IC1743.
  • Gold MH, Foster TD, Adair MA, Burlinson K, Lewis T. Prevention of hypertrophic scars and keloids by the prophylactic use of topical silicone gel sheets following a surgical procedure in an office setting. Dermatologic Surgery 2001;27(7):641-4.
Karagoz 2009 {published data only}
  • Karagoz H, Yuksel F, Ulkur E, Evinc R. Comparison of efficacy of silicone gel, silicone gel sheeting, and topical onion extract including heparin and allantoin for the treatment of postburn hypertrophic scars. Burns 2009;35(8):1097-103.
Kelemen 2007 {published data only}
  • Kelemen O, Kollar L, Menyhei G. A comparative clinical study of the treatment of hypertrophic scars with either intralaesional steroid or silicone gel sheeting [Hungarian]. Magyar Sebeszet 2007;60(6):297-300.
Li-Tsang 2006 {published and unpublished data}
  • Li-Tsang CW, Lau JC, Choi J, Chan CC, Jianan L. A prospective randomized clinical trial to investigate the effect of silicone gel sheeting (Cica-Care) on post-traumatic hypertrophic scar among the Chinese population. Burns 2006;32(6):678-83.
Li-Tsang 2010 {published and unpublished data}
  • Li-Tsang CWP, Zheng YP, Lau JCM. A randomized clinical trial to study the effect of silicone gel dressing and pressure therapy on posttraumatic hypertrophic scars. Journal of Burn Care and Research 2010;31(3):448-57.
Momeni 2009 {published data only}
Niessen 1998 {published and unpublished data}
  • Niessen FB, Spauwen PH, Robinson PH, Fidler V, Kon M. The use of silicone occlusive sheeting (Sil-K) and silicone occlusive gel (Epiderm) in the prevention of hypertrophic scar formation. Plastic and Reconstructive Surgery 1998;102(6):1962-72.
Pacquet 2001 {published data only}
Palmieri 1995 {published data only}
Sproat 1992 {published data only}
Tan 1999 {published data only}
  • Tan E, Chua SH, Lim JTE. Topical silicone gel sheet versus intralesional injections of triamcinolone acetonide in the treatment of keloids - a patient-controlled comparative clinical trial. Journal of Dermatological Treatment 1999;10(4):251-4.
Wigger-Alberti 2009 {published data only}
  • Wigger-Alberti W, Kuhlmann M, Wilhelm D, Mrowietz U, Eichhorn K, Ortega J, et al. Efficacy of a polyurethane dressing versus a soft silicone sheet on hypertrophic scars. Journal of Wound Care 2009;18(5):208-14.
Wittenberg 1999 {published data only}
  • Wittenberg GP, Fabian BG, Bogomilsky JL, Schultz LR, Rudner EJ, Chaffins ML, et al. Prospective, single-blind, randomised, controlled study to assess the efficacy of the 585-nm flashlamp-pumped pulsed-dye laser and silicon gel sheeting in hypertrophic scar treatment. Archives of Dermatology 1999;135(9):1049-55.

References to studies excluded from this review

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. Additional references
Al-Mandeel 1998 {published data only}
  • Al-Mandeel MS, Bang RL, Ebrahim MK. Re-appraisal of Cica-Care (silicone gel sheet) in the treatment of hypertrophic and keloid scars. Saudi Medical Journal 1998;19(6):741-5.
Berman 1999 {published data only}
Berman 2008 {published data only}
  • Berman B, Patel J, Perez O, Viera M. A prospective, randomized, investigator-blinded, placebo-controlled, comparative study evaluating the tolerability and efficacy of two topical medications versus placebo for the treatment of keloids and hypertrophic scars. Journal of the American Academy of Dermatology 2008;58(2):45.
Chan 2005 {published data only}
  • Chan KY, Lau CL, Adeeb SM, Somasundaram S, Nasir-Zahari M. A randomized, placebo-controlled, double-blind, prospective clinical trial of silicone gel in prevention of hypertrophic scar development in median sternotomy wound. Plastic and Reconstructive Surgery 2005;116(4):1013-20.
Chernoff 2007 {published data only}
  • Chernoff WG, Cramer H, Su-Huang S. The efficacy of topical silicone gel elastomers in the treatment of hypertrophic scars, keloid scars, and post–laser exfoliation erythema. Aesthetic Plastic Surgery 2007;31(5):495-500.
Chuangsuwanich 2000 {published data only}
  • Chuangsuwanich A, Osathalert V, Muangsombut S. Self-adhesive silicone gel sheet: a treatment for hypertrophic scars. Journal of Medical Association of Thailand 2000;83(4):439-44.
Clugston 1995 {published data only}
D'Andrea 2002 {published data only}
de Giorgi 2009 {published data only}
Dockery 1994 {published data only}
  • Dockery GL, Nilson RZ. Treatment of hypertrophic and keloid scars with SILASTIC gel sheeting. Journal of Foot and Ankle Surgery 1994;33(2):110-9.
Donati 1991 {published data only}
  • Donati L, Blandini D, Buraruffaldi Preis FW, Campiglio GL, Capretti A. Silicone gel in the treatment of hypertrophic scars following thermal injury. Rivista Italiana di Chirugia Plastica 1991;23(4):357-65.
Fulton 1995 {published data only}
  • Fulton JE Jr. Silicone gel sheeting for the prevention and management of evolving hypertrophic and keloid scars. Dermatological Surgery 1995;21(11):403-4.
Gold 1993 {published data only}
  • Gold MH. Topical silicone gel sheeting in the treatment of hypertrophic scars and keloids: a dermatological experience. Journal of Dermatologic Surgery and Oncology 1993;19(10):912-6.
Harte 2009 {published data only}
  • Harte D, Gordon J, Shaw M, Stinson M, Porter-Armstrong A. The use of pressure and silicone in hypertrophic scar management in burns patients: a pilot randomized controlled trial. Journal of Burn Care and Research 2009;30(4):632-42.
Hirshowitz 1993 {published data only}
  • Hirshowitz B, Ullman Y, Har-Shai Y, Vilenski A, Peled IJ. Silicone occlusive sheeting (SOS) in the management of hypertrophic and keloid scarring, including the possible mode of action of silicone by static electricity. European Journal of Plastic Surgery 1993;16(1):5-9.
Hollands 1999 {published data only}
  • Hollands R, Spyrou NM. Elemental composition changes between breast tissue with and without silicone gel sheeting and hypertrophic scar tissue. Biological Trace Element Research 1999;Winter(71-2):575-83.
Hosnuter 2007 {published data only}
  • Hosnuter M, Payasli C, Isikdemir A, Tekerekoglu B. The effects of onion extract on hypertrophic and keloid scars. Journal of Wound Care 2007;16(6):251-4.
Jenwitheesuk 2012 {published data only}
  • Jenwitheesuk K,  Surakunprapha P,  Jenwitheesuk K,  Kuptarnond C,  Prathanee S,  Intanoo W. Role of silicone derivative plus onion extract gel in presternal hypertrophic scar protection: a prospective randomized, double blinded, controlled trial. International Wound Journal 2012;9(4):397-402.
Katz 1995 {published data only}
Klopp 2000 {published data only}
  • Klopp R, Niemer W, Fraenkel M, von der Weth A. Effect of four treatment variants on the functional and cosmetic state of matures scars. Journal of Wound Care 2000;9(7):319-24.
Lee 1996 {published data only}
Loeding 1993 {published data only}
  • Loeding LA,  Guccione JM,  Mustoe TA,  Monafo WW,  Edwards DF,  Khouri RK. Effects of silicone gel on scar tissue in hand injuries. Journal of Hand Therapy 1993;6(1):59.
Mercer 1989 {published data only}
Musgrave 2002 {published data only}
  • Musgrave MA, Umraw N, Fish JS, Gomez M, Cartotto RC. The effect of silicone gel sheets on perfusion of hypertrophic burn scars. Journal of Burn Care and Rehabilitation 2002;23(3):208-14.
Muti E 1994 {published data only}
  • Muti E, Bovetto G, Bogetti P, Balocco P, Bonesi A, Bocchiotti G, et al. The use of silicone gel in hypertrophic scars and keloids. Rivista Italiana di Chirugia Plastica 1994;26(3):277-82.
Nikkonen 2001 {published data only}
Reish 2008 {published data only}
Ricketts 1996 {published data only}
  • Ricketts T, Saed GM, Fivenson DP. Cytokine mRNA changes during the treatment of hypertrophic scars with silicone and nonsilicone gel dressings. Dermatological Surgery 1996;22(11):955-9.
Sawada 1990 {published data only}
Shigeki 1999 {published data only}
  • Shigeki S, Nobuoka N, Murakami T, Ikuta Y. Release and skin distribution of silicone-related compound(s) from a silicone gel sheet in vitro. Skin Pharmacology and Applied Skin Physiology 1999;12(5):284-8.
Signorini 2007 {published data only}
  • Signorini M, Clementoni MT. Clinical evaluation of a new self-drying silicone gel in the treatment of scars: a preliminary report. Aesthetic Plastic Surgery 2007;31(2):183-7.
So 2003 {published data only}
  • So K, Umraw N, Scott J, Campbell K, Musgrave M, Cartotto R. Effects of enhanced patient education on compliance with silicone gel sheeting and burn scar outcome: a randomized prospective study. Journal of Burn Care and Rehabilitation 2003;24(6):411-7; discussion 410.
Steinstraesser 2011 {published data only}
  • Steinstraesser L,  Flak E,  Witte B,  Ring A,  Tilkorn D,  Hauser J,  et al. Pressure garment therapy alone and in combination with silicone for the prevention of hypertrophic scarring: randomized controlled trial with intraindividual comparison. Plastic and Reconstructive Surgery 2011;128(4):306e-13e.
Stoffels 2010 {published data only}
  • Stoffels I, Wolter TP, Sailer AM, Pallua N. The impact of silicone spray on scar formation. A single-center placebo-controlled double-blind trial. Der Hautarzt; Zeitschrift fur Dermatologie, Venerologie, und verwandte Gebiete  2010;61(4):332-8.
Suetake 2000 {published data only}
Van den K 2001 {published data only}
  • van den Kerchove E, Stappaerts KHM, Boeckx WD, Staes F, van den Hof B, Monstrey S, et al. The influence of different occlusive plates on the erythema of hypertrophic burn scars. European Journal of Plastic Surgery 2001;24(4):182-5.
van der Wal 2010 {published data only}
  • Van Der Wal MB, Van Zuijlen PPM, Van De Ven P, Middelkoop, E. Topical silicone gel versus placebo in promoting the maturation of burn scars; A randomized controlled trial. Burns 2011;37:S4.
  • van der Wal MBA, van Zuijlen PP, van de Ven P, Middelkoop E. Topical silicone gel versus placebo in promoting the maturation of burn scars: a randomized controlled trial. Plastic and Reconstructive Surgery  2010;126(2):524-31.
Widgerow 2000 {published data only}
  • Widgerow AD, Chait LA, Stals PJ. Triple keloid therapy: a combination of steroids, surgery and silicone gel strip/sheet for keloid treatment. European Journal of Plastic Surgery 2000;23(3):150-1.

References to studies awaiting assessment

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. Additional references
Fonseca Capdevila 2007 {published data only}
  • Fonseca Capdevila E, López Bran E, Fernández Vozmediano JM, de la Torre Fraga, Nasarre IQ, Moreno Giménez JC. Prevention of scar sequels after excision of benign cutaneous lesions: multicentre, prospective, open label, controlled study comparing silicone gel versus silicone sheets in 131 patients with melanoctyic nevi [Prevención de secuelas cicatrizales de la extirpación de lesiones cutáneas benignas: estudio multicéntrico, prospectivo, abierto y controlado que compara un gel de silicona y láminas de silicona en 131 pacientes con nevos melanocíticos]. Piel 2007;22(9):421-6.
Quddus-ur-Rehman 2012 {published data only}
  • Quddus-ur-Rehman Latif U, Saqib AS, Elahi A. Comparison of different modalities of treatment of hypertrophic scars and keloids. Medical Forum Monthly  2012;23(3):7-11.

Additional references

  1. Top of page
  2. Abstract
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. What's new
  13. History
  14. Contributions of authors
  15. Declarations of interest
  16. Sources of support
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. Additional references
Beers 1999
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Carney 1993
  • Carney SA. Hypertrophic scar formation after skin injury. Journal of Wound Care 1993;2(5):299-302.
Cruz-Korchin 1997
  • Cruz-Corchin NI. Reply to letter by F Niessen, MD. Annals of Plastic Surgery 1997;38(5):547.
Davey 1991
Eisenbeiss 1998
  • Eisenbeiss W, Peter FW, Bakhtiari C, Frenz C. Hypertrophic scars and keloids. Journal of Wound Care 1998;7(5):255-7.
Higgins 2011
  • Higgins JPT, Altman DG, Sterne JAC. Chapter 8: Assessing risk of bias in included studies. In: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
Katz 1992
Lefebvre 2011
  • Lefebvre C, Manheimer E, Glanville J, on behalf of the Cochrane Information Retrieval Methods Group. Chapter 6: Searching for studies. In: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011]. The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.
O'Sullivan 1996
  • O'Sullivan ST, O'Shaughnessy M, O'Connor TPF. Aetiology and management of hypertrophic scars and keloids. Annals of the Royal College of Surgeons of England 1996;78(3 Pt 1):168-75.
Perkins 1982
Quinn 1985
Raney 1993
  • Raney RW. Keloid Pathophysiology and Management. Grand Rounds Archive. The Baylor College of Medicine, Houston 1993.
Sawada 1992
Shaffer 2002
Shakespeare 1993
  • Shakespeare P. Burn wound healing. Journal of Tissue Viability 1993;3(1):16-24.
SIGN 2012
  • Scottish Intercollegiate Guidelines Network (SIGN). Search filters. http://www.sign.ac.uk/methodology/filters.html#random (accessed 30 August 2012).
Smith & Nephew 2000
  • Smith, Nephew. Cica-Care: Scar Treatment Gel Sheet. Product instruction leaflet 2000.
Swanson 1974
Thomas 1997
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