Ruzicka 1990.

Study characteristics
Methods	RCT, placebo‐controlled, double‐blind Date of study: December 1986 ‐ March 1988 Location: 7 centres in Germany
Participants	Randomised: 82 participants (mean age 44 years, 55 male) Inclusion criteria Aged 18 ‐ 75 Generalised chronic plaque or exanthematic Exclusion criteria Pregnancy, kidney insufficiency, liver insufficiency Had uncontrolled cardiovascular disorder Had uncontrolled diabetes Had uncontrolled hypertension Dropouts and withdrawals 4/82 (5%) Acitretin (2) overweight and dyslipidaemia Placebo (2) erythrodermia
Interventions	Intervention A. Acitretin, orally, 35 mg, daily, 8 weeks (n = 42) Control intervention B. Placebo, orally, daily, 8 weeks (n = 40)
Outcomes	Assessments at 8 weeks Primary outcomes of the trial PASI Secondary outcomes of the trial Side effects
Notes	Funding sources: 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 483): "The study was designed as a randomized, double‐blind, placebo‐controlled parallel group trial" Comment: no description of the method used to guarantee random sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote (p 483): "The study was designed as a randomized, double‐blind, placebo‐controlled parallel group trial" Comment: no description of the method used to guarantee allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	High risk	Quote (p 483): "The study was designed as a randomized, double‐blind, placebo‐controlled parallel group trial" Comment: no description of the method used to guarantee blinding as visible side effects are related to acitretin
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote (p 483): "The study was designed as a randomized, double‐blind, placebo‐controlled parallel group trial... the investigators blinded to treatment assignment" Comment: no description of the method used to guarantee blinding of outcome assessment as visible side effects are related to acitretin
Incomplete outcome data (attrition bias) All outcomes	Low risk	82 included/78 analysed Quote (p 483): "... according to the intention‐to‐treat principle.. Dropout data were evaluated on the date of dropout" Comment: probably done
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol was available. The prespecified outcomes mentioned in the Methods section appeared to have been reported