Nugteren‐Huying 1990.

Study characteristics
Methods	RCT, active/placebo‐controlled, double‐blind Date of study: not stated Setting: multicentre in the Netherlands
Participants	Randomised: 39 participants (mean age 44 years, 27 male) Inclusion criteria Participants with moderate‐severe psoriasis (BSA ≥ 10) Exclusion criteria Pregnancy, kidney insufficiency, liver insufficiency Had uncontrolled cardiovascular disorder Dropouts and withdrawals 5/39 (12.8%) Time and reason: not stated
Interventions	Intervention A. Dimethylfumarate (n = 12), orally, 120 mg, gradual increase 1 ‐ 6 tablets, once a day, 16 weeks Control intervention B. Octyl hydrogen fumarate (n = 10), orally, 284 mg, gradual increase 1 ‐ 6 tablets, once a day, 16 weeks C. Placebo (n = 12), orally, once a day, 16 weeks
Outcomes	Assessments at 16 weeks Primary outcomes of the trial BSA Secondary outcomes of the trial Score of infiltration and scaling Side effects
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 331): "The patients were randomly assigned..." Comment: no description of the method used to guarantee random sequence generation
Allocation concealment (selection bias)	Unclear risk	Quote (p 331): "The patients were randomly assigned..." Comment: no description of the method used to guarantee allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote (p 331): “The double‐blind treatment lasted 16 weeks for each patients... All tablets (provided by Fumapharm AG, Muri, Switzerland) had the same appearance, size and colour” Comment: probably done
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote (p 331): “The double‐blind treatment lasted 16 weeks for each patients...All tablets (provided by Fumapharm AG, Muri, Switzerland) had the same appearance, size and color” Comment: probably done
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Randomly assigned 39, analysed 34 Comment: no description of the method used to perform analyses of the primary outcome and to manage missing data
Selective reporting (reporting bias)	Unclear risk	Comment: no protocol was available. The prespecified outcomes mentioned in the Methods section appeared to have been reported