ElRefaei 2015.

Study characteristics
Methods	Aim of study: to evaluate the efficacy and the tolerability of a combination of 20% salicylic–10% mandelic acid peel against a 35% glycolic acid peel in the treatment of active AV Design: parallel Unit of allocation: individuals Allocation: sealed envelope method was used Blinding: assessor‐blind Duration of trial (from recruitment to last follow‐up): conducted from March 2012 to March 2013 Dropouts: no dropouts
Participants	Population description: participants with facial AV Setting: Dermatology and Andrology Department of Beha University hospital, Egypt Randomised number: 40 Age: 14 to 29 years; 35% glycolic acid peel: 19.55 ± 4.19; 20% salicylic–10% mandelic acid peel: 19.8 ± 4.02 Sex (M/F): 35% glycolic acid peel (5/15); 20% salicylic–10% mandelic acid peel (3/17) Severity of illness: moderate to severe, 20 participants in 20% salicylic–10% mandelic acid peel had moderate acne compared with 19 participants with moderate acne and one with severe acne in GAP
Interventions	Name of treatment group: glycolic acid n = 20 Description: 35% glycolic acid peel Treatment period: 12 weeks Timing: seven peeling sessions were conducted for each group every two weeks Name of treatment group: 20% salicylic–10% mandelic acid peel n = 20 Description: 20% salicylic–10% mandelic acid peel Treatment period: 12 weeks Timing: seven peeling sessions were conducted for each group every two weeks
Outcomes	Primary outcomes Participants' global self‐assessment of acne improvement (e.g. measured by a 4‐point scale: excellent, good, fair, and poor). Week 12; a 3‐point visual analogue scale: poor < 30% improvement, fair 30% to 60% improvement, and good > 60% improvement Withdrawal for any reason. No withdrawals Secondary outcomes Change in lesion counts (total or inflamed and non‐inflamed separately). Reduction of inflamed and non‐inflamed lesions, from baseline to week 20. Physicians' global evaluation of acne improvement. Week 4, 8, 12, and 20; a five‐point visual analogue scale (VAS): (1) worse, (2) no change, (3) poor (< 30% improvement), (4) fair (31% to 60% improvement), and (5) good (> 60% improvement) Minor adverse events (assessed as total number of participants who experienced at least one minor adverse event). Reported total number of participants who experienced adverse events Quality of life. Authors did not report this outcome Other outcomes that were not analysed in this review Post‐acne hyperpigmentation and scars Michaelsson severity index
Notes	Funding: not described
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: " This randomised clinical trial was carried out on 40 patients who were divided randomly, by the sealed envelope method…". Comment: sealed envelope method was used
Allocation concealment (selection bias)	Low risk	Quote: " This randomised clinical trial was carried out on 40 patients who were divided randomly, by the sealed envelope method…". Comment: sealed envelope method was used
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	This was not stated
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Two uninvolved dermatologists made a subjective assessment…". Comment: blinding probably sufficient
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "All of them (32 females and eight males) completed the study." Comment: no missing outcome data
Selective reporting (reporting bias)	Low risk	Results reported for all prespecified outcomes in the methods section
Other bias	Low risk	No other potential bias identified