Weltert 2004.

Study characteristics
Methods	Aim of study: to compare the efficacy of nicotinamide to a reference comparative product in the local treatment of moderate acne with a predominant inflammatory component, i.e. erythromycin Design: parallel, active control Unit of allocation: individuals Allocation: randomisation; no details Blinding: unclear Duration of trial (from recruitment to last follow‐up): not described Dropouts: 7 in treatment; 5 in control
Participants	Population description: acne with inflammatory predominance Setting: Laboratoire Dermscan (Villeurbanne), France, all subjects were Caucasian. Randomised number: 158 Age: 19.0 +/‐ 2.7 in treatment; 19.3 +/‐ 2.9 in control Sex (M/F): 29/50 in treatment; 29/50 in control Severity of illness: moderate inflammatory acne on face (≥ 5 inflammatory elements, papules or pustules)
Interventions	Name of treatment group: 4% nicotinamide gel; n = 79 Description: product: Exfoliac NC Gel (Merck Medication Familiale, France) Galenic form: gel Formula: active ingredient: niacinamide 4% Excipients: aqua, alcohol denat., laureth‐12, magnesium aluminium silicate, hydroxypropyl methyl cellulose, citric acid Treatment period: 8 weeks Timing: twice daily Name of treatment group: erythromycin; n = 79 Description: erythromycin, titre 1000 UI/mg Galenic form: liquid gel for local application Formula: active ingredient: erythromycin 4% Excipients: 96% ethyl alcohol, hydroxypropyl cellulose Treatment period: 8 weeks Timing: twice daily
Outcomes	Primary outcomes Participants' global self‐assessment of acne improvement (e.g. measured by a four‐point scale: excellent, good, fair, and poor). Authors did not report this outcome Withdrawal for any reason. 12 withdrawals during the 8‐week treatment period Secondary outcomes Change in lesion counts (total or inflamed and non‐inflamed separately). Reduction of inflamed and non‐inflamed lesions, week 8 Physicians' global evaluation of acne improvement. Authors did not report this outcome Minor adverse events (assessed as total number of participants who experienced at least one minor adverse event). Reported percentage of participants who experienced minor adverse event Quality of life. Authors did not report this outcome Other outcomes that were not analysed in this review Intensity of seborrhoea
Notes	Funding: not mentioned
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Although 'randomised' was mentioned, no details were reported for random sequence generation.
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Low risk	7 and 5 dropouts in treatment and control group. No imputation method reported, but number of missing data not considered as likely to introduce bias significantly
Selective reporting (reporting bias)	Unclear risk	Insufficient data regarding "Safety" assessed through clinical scoring
Other bias	Low risk	No other potential bias identified

all‐TRA: all‐trans retinoic acid
AQOL: Acne quality of life
AV: acne vulgaris
AZA: azelaic acid
BPO: benzoyl peroxide
CDP: clindamycin phosphate
CLN: clindamycin
ITT: intention‐to‐treat
MAS: Michaelsson acne severity
RA: retinoic acid
SA: salicylic acid
SD: standard deviation