Wright 1993.

Methods	Randomized, double‐blind, placebo‐controlled trial. Patients were assessed at entry, after 3 weeks, and after 3, 6, 9 and 12 months. Sigmoidoscopy was performed at each visit. Biopsy was taken at entry, 6 months and 1 year
Participants	Patients, ages 18 to 75 years, with inactive ulcerative colitis who were asymptomatic for not less than one week and not more than one month prior to entry (N = 101). Steroid or SASP therapy was stopped at least one week prior to entry
Interventions	Olsalazine 2 g/day (500 mg capsules 4 times per day; n = 49) or matching placebo (n = 52) for 1 year
Outcomes	Clinical relapse was defined as a relapse of diarrhea (with or without blood and mucous) thought by the attending physician to warrant introduction of rectal or oral corticosteroids
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Low risk	Adequate
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐blind: matching placebo
Incomplete outcome data (attrition bias) All outcomes	Low risk	3 patients from the placebo group did not complete the study (1 lost top follow up, 1 lost to compliance, 1 initial protocol exclusion)
Selective reporting (reporting bias)	Low risk	Expected outcomes were reported
Other bias	Low risk	The study appears to be free of other sources of bias

UC‐DAI = Ulcerative Colitis Disease Activity Index