Prendiville 1988.

Methods	Parallel design, randomised controlled trial
Participants	40 participants from two centres: Ealing Hospital at Middlesex and St John's Hospital for Diseases of the Skin at London, United Kingdom Inclusion criteria: not provided Exclusion criteria: not provided Age: for all participants, ranged from 16 to 31 years Gender: 100% male Duration of acne: not provided Acne severity: severe
Interventions	Group 1 (n = 20): dapsone 100 mg/daily Group 2 (n = 20): 13‐cis‐retinoic acid (oral isotretinoin) 40 mg/daily Interventions were administered for 16 weeks
Outcomes	Reduction in lesion counts (only pustules, nodules and cysts) on the face, anterior neck, and trunk (chest and back)* Improvement in photographic evaluation assessed by grading slide from each participants at each visit using the acne grading scale (0‐10) proposed by Cunliffe (Cunliffe 1981). Colour slides were produced from a standard set of photographs taken of the face and neck, chest, and back Subjective improvement assessed by each participant by a visual analogue scale ranging from – 5 to + 5* Sebum excretion rate measured from forehead skin by a gravimetric method (Cunliffe 1969; Cunliffe 1975; Pochi 1991) Analysis of aerobic and anaerobic skin surface microflora assessed by samples taken from the participants’ forehead using the ‘scrub' technique (Williamson 1965)* Laboratory and clinical side effects* Reasons for withdrawal* Assessments for all outcomes were made at 0, 4, 8, 16, 20, 28, and 36 weeks Indicates outcomes which matched those prespecified for this review
Funding body	Roche Products Limited
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: The trial did not provide any information about random sequence generation
Allocation concealment (selection bias)	Unclear risk	Comment: There was no statement regarding methods of allocation concealment in the study
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote: “In view of the mucocutaneous side‐effects of 13‐cis retinoic acid which make double‐blind assessment of this drug impossible, our study was conducted on a single‐blind basis”. “Each slide was graded blind using the acne grading scale (0‐10)”. Comment: Participants and personnel were not blinded; they were aware of the treatment arm to which participants were allocated
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "...our study was conducted on a single‐blind basis.” “Each slide was graded blind using the acne grading scale (0‐10)”. Comment: The blinding of outcome assessment was clearly stated only for one of the five outcomes of the study
Incomplete outcome data (attrition bias) All outcomes	High risk	Quote: "Six patients failed to complete the study, three in each group. Four patients, one on dapsone and three on 13‐cis retinoic acid were withdrawn because of non‐attendance or failure to take medication as directed". Comment: Reasons for attrition were described and there was imbalance of missing data between intervention groups
Selective reporting (reporting bias)	High risk	Comment: No protocol available. Besides this, one outcome, subjective improvement assessed by each participant by a visual analogue scale, was not reported using the measures prespecified on the methods section (only P values at each time point of measurement were reported)
Other bias	Unclear risk	Comment: The study might be at risk of inappropriate influence of funders, as it was promoted by a pharmaceutical company