Saurat 1988.

Study characteristics
Methods	RCT, active/placebo‐controlled, double‐blind study Date of study: not stated Location: 6 centres in France and Switzerland
Participants	Randomised: 42 participants Inclusion criteria BSA > 20% Exclusion criteria Kidney insufficiency, liver insufficiency, had uncontrolled cardiovascular disorder Baseline characteristics N = 42, mean age of 44.5 years, 32 male Dropouts and withdrawals 7/65 (11%)
Interventions	Intervention A. Acitretin (n = 20), orally, 2 x 25/d 2 weeks and 25/d + UVA 3/week, daily, 10 weeks Control intervention B. Placebo, orally (n = 22), daily, 10 weeks Co‐intervention: UVA 3/week, 10 weeks
Outcomes	Assessments not clearly stated (reported at 8 weeks) Primary outcomes Not clearly stated Outcomes Change in PASI Time to clear AEs
Notes	Funding source: not stated Declarations of interest: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote (p 219): "This multicenter study was performed in a double‐blind, parallel fashion... The patients were randomly allocated to ..." Comment: no description of the method used to guarantee random sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote (p 219): "This multicenter study was performed in a double‐blind, parallel fashion... The patients were randomly allocated to ..." Comment: no description of the method used to guarantee allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote (p 219): "This multicenter study was performed in a double‐blind, parallel fashion...All patients initially received 2 capsules of test medication (placebo, acitretin 2x25 mg, ...." Comment: no description of the method used to guarantee blinding of outcome assessment with visible AEs in both acitretin and etretinate groups
Blinding of outcome assessment (detection bias) All outcomes	High risk	Comment: no description of the method used to guarantee blinding of outcome assessment with visible AEs in both acitretin and etretinate groups
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Quote (p 220): "Patients who left the study ... were not included in the evaluation of efficacy". Comment: no ITT analyses (number lost to follow‐up unknown)
Selective reporting (reporting bias)	Low risk	Comment: no protocol was available. The prespecified outcomes mentioned in the Methods section appeared to have been reported.