| Methods |
Two‐center, randomized, parallel group dose‐ranging study |
| Participants |
Adult patients with ulcerative colitis in remission (N = 198) for three or more months. Remission was defined as no clinical symptoms of active disease and no signs of active inflammation on sigmoidoscopy (grade 0 or 1: normal or pink mucosa of quiescent colitis without visible vessels) |
| Interventions |
Olsalazine at a dose of 0.5 g/day (n = 67), 1.0 g/day (n = 65) or 2.0 g/day (n = 62) for 12 months |
| Outcomes |
Primary: relapse defined as an increase in bowel frequency with blood or mucus and evidence of active disease on sigmoidoscopy. Secondary: time in remission from start of treatment, laboratory measurements, adverse events |
| Notes |
4 patients did not receive any study drugs and were excluded from the ITT analysis |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Not described |
| Allocation concealment (selection bias) |
Unclear risk |
Not described |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Double‐blind: patients in the lower dose group took a physically indistinguishable placebo |
| Incomplete outcome data (attrition bias)
All outcomes |
Unclear risk |
19% of the 0.5 g/day group withdrew before the end of the study compared to 14% of the 1.0 g/day group and 24% of the 2.0 g/day group. Reasons for withdrawal are described but are not attributed to individual treatment groups |
| Selective reporting (reporting bias) |
Low risk |
Expected outcomes are reported |
| Other bias |
Low risk |
The study appears to be free of other sources of bias |
