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Summary

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

This review highlights clinically important findings about acne treatment identified in nine systematic reviews published or indexed in the period March 2009 to February 2010. A systematic review of dietary influences on acne suggested that a possible role of dietary factors in acne cannot be dismissed, as the studies to date have not been sufficiently large or robust. Another review looked at benzoyl peroxide, which may be enjoying a comeback because of increasing bacterial resistance to antibiotics, and suggested that there was a lack of evidence that stronger preparations were more effective than weaker ones. The same team also carried out a systematic review addressing the question of whether topical retinoids cause an initial worsening of acne. They found no evidence to suggest initial worsening of acne severity, although there was evidence of skin irritation that typically settled by 8–12 weeks. A review of oral isotretinoin and psychiatric side-effects reinforced a possible link between the two, although it pointed out that the better-quality primary studies were still inconclusive. An updated Cochrane Review confirmed the efficacy of combined oral contraceptives (COCs) in reducing acne lesion counts. It also found that the evidence to support COCs containing cyproterone acetate over others was very limited. Another Cochrane Review failed to show any benefit of spironolactone for acne, based on limited studies. Three reviews examined laser and light therapies, and found some evidence of superiority only for blue or blue/red light treatment over placebo light, but a general absence of comparisons against other acne treatments. Photodynamic therapy had consistent benefits over placebo but was associated with significant side-effects and was not shown to be better than topical adapalene.


Background

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

This review summarizes nine systematic reviews dealing with treatment and prevention of acne, which were indexed in bibliographic databases between March 2009 and February 2010 and were included in the 2010 Annual Evidence Update on Acne Vulgaris from NHS Evidence – skin disorders. This review aims to pick out clinically important points with the busy clinician in mind. Readers are encouraged to view the full report and original papers cited in the 2010 Annual Evidence Update (http://www.library.nhs.uk/skin/ViewResource.aspx?resID=343542&tabID=289&catID=8275), where the methods and omitted citations are given. This review considers systematic reviews only, as they are generally considered to be the most reliable evidence source, whereas the results of single randomized controlled trials (RCTs) are often contradicted by subsequent trials.1 A paper summarizing the results of the 2008 and 2009 Annual Evidence Updates on Acne Vulgaris has previously been published in this journal.2

Associations

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

Diet

Spencer et al.3 undertook a systematic review of dietary influences in acne that included 21 observational studies and 6 RCTs. These suggested that dairy products (especially milk) are associated with increased risk and greater severity of acne, and that a low glycaemic load diet might improve the condition. The question of whether chocolate worsens acne remained unanswered. The reviewed lacked a thorough assessment of study quality, and most included studies were observational in design with self-reported outcomes, which may be a significant bias in this type of study. The glycaemic diet trial4 was published in duplicate5 and also as a third paper reporting a subgroup.6 The authors of the systematic review included two of these as separate trials, highlighting the problem of disproportionate effects of duplicate publications.7

Treatments

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

Benzoyl peroxide

Fakhouri et al.8 revisited benzoyl peroxide as a potential solution to the problem of antibiotic resistance in acne, looking at usage methods to increase efficacy and minimize irritancy. A PubMed search returned 900 reports. The authors concluded that efficacy was similar for 2.5%, 5% and 10% preparations of benzoyl peroxide, and that efficacy may be enhanced by vitamin E and tertiary amines, and by combining with retinoids. New delivery systems increase tolerability without compromising efficacy. The review was not performed to a high standard. The inclusion criteria for studies were unclear, and those studies included were not assessed for quality. No attempt was made to combine the studies (i.e. meta-analysis). The overall conclusion on equivalence was based on just one study that was probably underpowered to determine equivalence.9

Topical retinoids

A review by the same team investigated whether initial use of topical retinoids paradoxically increases acne lesion counts in the first fortnight.10 They did not specify study types, numbers or quality assessments, or explain their selective citation of studies. Eight studies found no evidence of worsening and one suggested slight early deterioration. Irritation was common, but normally settled by weeks 8 to 12. This review was conducted by a team whose research centre is supported by Galderma, the manufacturers of adapalene, and the topic seemed slightly contrived. However, it confirms that skin irritation is common with topical retinoids and that it takes 2–3 months before tolerance occurs.

Oral isotretinoin and depression

A recent systematic review by a team of psychiatrists addressed the key question of whether oral isotretinoin is linked to depression.11 MEDLINE and EMBASE were searched, but no other methodology was specified. The authors found 24 case reports and series that apparently suggested a link, but such reports are very prone to publication bias.12 Some reports described clear symptom cessation when stopping isotretinoin, and recurrence on restarting. Two large database studies found no association, and two found slightly increased antidepressant use. A case crossover study of 30 000 people with acne found that those developing depression were 2.68 times more likely to have taken isotretinoin in the preceding 5 months.13 Only two small trials were controlled, with neither reporting increased psychiatric side-effects. Study selection and quality assessment within this review were not clear. Severe acne is itself associated with depression. The authors state the evidence strongly supports a link as ‘a great number of reports… support this’. However, the better-quality studies included in their review were inconclusive, and publication bias is a concern. The review has added little to the debate, although it does include some interesting discussion about plausible mechanisms by which retinoids affect the central nervous system.

Oral contraceptives and antiandrogens

An updated Cochrane Review examined 25 trials of combined oral contraceptive pills (COCs) in acne.14 Six compared COCs to placebo, and confirmed their superiority in reducing lesion counts. COCs containing cyproterone acetate (CPA) are traditionally used for acne, but evidence of superiority over other COCs was limited and inconclusive. Of 13 direct comparisons of different COCs, methodological diversity and conflicting results prevented conclusions. One small study compared CPA with minocycline 50 mg, which produced similar self-assessed improvements in acne. The analysis was generally hampered by high dropout rates, weak design and poor reporting.

A second updated Cochrane Review considered spironolactone for hirsutism and/or acne,15 but only three studies were relevant for acne. Sebum excretion rate was not reduced in a study that compared spironolactone 3% and 5% cream against topical canrenoate (a metabolite) in 31 patients.16 A double-blinded cross-over RCT17 compared oral spironolactone 200 mg with placebo in 29 women. The authors of that report claimed significant reductions in mean inflamed lesion counts, but they did not perform an intention-to-treat analysis. The spironolactone group was more severe at baseline, and the imbalance was not adjusted in the analysis, which meant that those in the active group might have simply improved with time (regression to the mean). Another excluded study compared four doses of spironolactone against placebo.18 Those authors claimed that doses of ≥ 100 mg resulted in improvement, yet they presented no statistics. The small numbers (n = 36) and multiple groups make statistical significance very unlikely.

Laser and light therapies and photodynamic treatment

Three new reviews have examined laser and light therapies for acne. The first, by Hamilton et al.,19 a team supported by the Cochrane Collaboration, was well reported. This review searched eight databases and comprised 694 patients from 25 RCTs. Trials varied widely in design and quality, and meta-analysis was impossible. Ten RCTs evaluated light vs. placebo, and found that green, yellow and infrared spectrums either showed no difference or slight improvement. A red light trial claimed significant improvement but was unblinded. Some evidence for superiority of blue or blue-red light over placebo was found in three studies, with reductions in inflammatory lesions of 49–75% vs. 10–25% in the untreated patients, with minimal side-effects. Three studies compared light therapies against other active topical comparators. Only one study found a significant benefit, with blue-red light reducing lesion counts to a greater degree than 5% benzoyl peroxide at week 8 (75% vs. 60%, = 0.02). Studies comparing blue light with topical clindamycin, and intense pulsed laser to intense pulsed light plus benzoyl peroxide, found no significant differences in outcomes. The review also included 12 small trials of light plus light-activated cream (photodynamic therapy; PDT), which showed more consistency, most suggesting benefit over light alone. However, the one active comparator trial reported PDT to be less effective in reducing inflammatory lesions compared with 1% adapalene gel at 12 weeks. Many participants on PDT experienced side-effects such as pain and peeling that were sufficiently severe to discontinue treatment.

The two other reviews specifically concerned PDT and acne. Riddle et al.20 added little, undertaking uncritical analysis of 8 trials and 13 case series from one database. All reported reduction in inflammatory lesions of 25–88% and/or significant improvement in acne, with consistent superiority of PDT over light alone. Pain, oedema and erythema featured in all studies, and in some participants, long-term photosensitivity was described. An unpublished multicentre RCT failed to show a difference between blue light with aminolaevulinic acid (ALA) or vehicle.

The other review on PDT attempted to answer practical questions on PDT use.21 A wider search found 5 randomized trials (4 were RCTs) and 16 other reports. Considering these, the authors favoured topical photosensitizers, shorter contact times, methyl aminolaevulinate over ALA, and lower light fluences, because of more tolerable side-effects. They recommended treating inflammatory and moderately severe acne and skin types I–III, using 2–4-week intervals to minimize side-effects. Although this was an interesting commentary, there was limited hard evidence to substantiate the guidance.

Clinical and research implications

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

The key learning points are summarized in the box below. The general quality of systematic reviews dealing with acne was poorer than those we have found on eczema and skin cancer, often limited by unclear study selection criteria and lack of critical appraisal of the quality of included studies. At best, the reviews have highlighted the need for further research, especially into comparing novel therapies such as light sources and laser against commonly used active comparators for a sustained period.

Learning points

  •  It is possible that a low glycaemic diet may help acne and that chocolate worsens acne; good-quality prospective studies are needed to resolve such uncertainties.
  •  Wider use of benzoyl peroxide is one means of possible reduction of bacterial resistance due to prolonged use of antibiotics.
  •  Although use of topical retinoids will often result in skin irritation during the first 8–12 weeks of treatment, they do not seem to worsen acne lesion counts during this period.
  •  Oral isotretinoin may be associated with depression, although the evidence to date is not entirely convincing. As better studies are awaited, it is prudent to continue to warn patients of a possible effect on depression and mood.
  •  There is good evidence that COCs are useful in reducing acne lesion counts. They should be given greater consideration for women with acne who need contraception.
  •  There is little evidence to support favouring COCs containing cyproterone acetate above other combined preparations for acne.
  •  There is no convincing evidence to support the use of topical or oral spironolactone for acne.
  •  Light and laser treatments have been shown to be of short-term benefit if patients can tolerate some initial discomfort.
  •  Light and laser therapies have not been shown to be better than simple topical treatments. Long-term benefits are unknown.
  •  Even though PDT is better than placebo for acne in the short term, it cannot be recommended at present for acne as a first-line treatment because of its unacceptable local side-effects.
  •  One comparative trial has shown that PDT was less effective than 1% adapalene in the short-term reduction of inflammatory lesions.

References

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

CPD questions

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

Learning objective

The purpose of this activity is to review recent developments in defining the causes and in the treatment of acne, and to demonstrate up-to-date knowledge relating to the management of acne.

Question 1

Benzoyl peroxide treatment may help which of the following acne problems?

a) Local skin irritation

b) Post-inflammatory skin pigmentation

c) Antibiotic resistance

d) Initial acne flaring

e) Incompliance

Question 2

Which of the following is recognised as a long-term side effect of laser treatment for acne?

a) Pain

b) Oedema

c) Photosensitivity

d) Erythema

e) Desquamation

Question 3

Which of the following have been shown to be effective at reducing acne lesion counts?

a) Milk exclusion diet

b) Testosterone

c) Topical spironolactone

d) Oral spironolactone

e) Combined oral contraceptives

Question 4

In a recent case-crossover study, participants with depression were how many times more likely to have taken isotretinoin in the preceding five months?

a) 1.48

b) 2

c) 2.68

d) 3

e) 3.68

Question 5

What is the reason for not currently recommending photodynamic therapy (PDT) as a first line treatment for acne?

a) It is no better than placebo

b) Unacceptable local side effects

c) Laser is better than PDT

d) The frequency of treatments required

e) Lack of long term benefit

Instructions for answering questions

  1. Top of page
  2. Summary
  3. Background
  4. Associations
  5. Treatments
  6. Clinical and research implications
  7. References
  8. CPD questions
  9. Instructions for answering questions

This learning activity is freely available online at http://www.wileyblackwellcme.com.

Users are encouraged to

  •  Read the article in print or online, paying particular attention to the learning points and any author conflict of interest disclosures
  •  Reflect on the article
  •  Register or login online at http://www.wileyblackwellcme.com and answer the CPD questions
  •  Complete the required evaluation component of the activity

Once the test is passed, you will receive a certificate and the learning activity can be added to your RCP CPD diary as a self-certified entry.