Comparison 1. 5‐ASA versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Failure to induce global/clinical remission	11	2387	Risk Ratio (M‐H, Fixed, 95% CI)	0.86 [0.82, 0.89]
1.1.1 Dose of 5‐ASA: < 2 g	3	231	Risk Ratio (M‐H, Fixed, 95% CI)	0.92 [0.84, 1.02]
1.1.2 Dose of 5‐ASA: 2 ‐ 2.9 g	8	956	Risk Ratio (M‐H, Fixed, 95% CI)	0.88 [0.82, 0.94]
1.1.3 Dose of 5‐ASA: ≥ 3 g	8	1200	Risk Ratio (M‐H, Fixed, 95% CI)	0.83 [0.77, 0.88]
1.2 Failure to induce global/clinical improvement (including remission)	14	2256	Risk Ratio (M‐H, Random, 95% CI)	0.68 [0.61, 0.75]
1.2.1 Dose of 5‐ASA: < 2 g	3	231	Risk Ratio (M‐H, Random, 95% CI)	0.79 [0.64, 0.97]
1.2.2 Dose of 5‐ASA: 2 ‐ 2.9 g	10	877	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.67, 0.88]
1.2.3 Dose of 5‐ASA: ≥ 3 g	9	1148	Risk Ratio (M‐H, Random, 95% CI)	0.57 [0.51, 0.65]
1.3 Failure to induce endoscopic remission	4	1154	Risk Ratio (M‐H, Random, 95% CI)	0.77 [0.67, 0.89]
1.3.1 Dose of 5‐ASA: < 2 g	1	122	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.64, 1.14]
1.3.2 Dose of 5‐ASA: 2 ‐ 2.9 g	3	393	Risk Ratio (M‐H, Random, 95% CI)	0.86 [0.70, 1.05]
1.3.3 Dose of 5‐ASA: ≥ 3 g	4	639	Risk Ratio (M‐H, Random, 95% CI)	0.70 [0.56, 0.87]
1.4 Failure to induce endoscopic improvement (including remission)	4	416	Risk Ratio (M‐H, Fixed, 95% CI)	0.71 [0.59, 0.86]
1.4.1 Dose of 5‐ASA: 2 ‐ 2.9 g	3	265	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.58, 0.92]
1.4.2 Dose of 5‐ASA: ≥ 3 g	2	151	Risk Ratio (M‐H, Fixed, 95% CI)	0.69 [0.49, 0.96]
1.5 Adverse events	8	1218	Risk Ratio (M‐H, Fixed, 95% CI)	0.95 [0.85, 1.07]
1.5.1 Dose of 5‐ASA: < 2 g	1	30	Risk Ratio (M‐H, Fixed, 95% CI)	1.26 [0.74, 2.13]
1.5.2 Dose of 5‐ASA: 2 ‐ 2.9 g	5	377	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.82, 1.33]
1.5.3 Dose of 5‐ASA: ≥ 3 g	5	811	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.80, 1.05]
1.6 Serious adverse events	4	746	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.18, 1.56]
1.6.1 Dose of 5‐ASA: 2 ‐ 2.9 g	3	243	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.14, 3.33]
1.6.2 Dose of 5‐ASA: ≥ 3 g	3	503	Risk Ratio (M‐H, Fixed, 95% CI)	0.44 [0.10, 1.92]
1.7 Withdrawals due to adverse events	13	2372	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.54, 0.97]
1.7.1 Dose of 5‐ASA: < 2 g	3	231	Risk Ratio (M‐H, Fixed, 95% CI)	0.55 [0.19, 1.63]
1.7.2 Dose of 5‐ASA: 2 ‐ 2.9 g	9	926	Risk Ratio (M‐H, Fixed, 95% CI)	1.13 [0.65, 1.94]
1.7.3 Dose of 5‐ASA: ≥ 3 g	9	1215	Risk Ratio (M‐H, Fixed, 95% CI)	0.59 [0.41, 0.87]
1.8 Exclusions and withdrawals after study entry	15	2529	Risk Ratio (M‐H, Random, 95% CI)	0.61 [0.51, 0.72]
1.8.1 Dose of 5‐ASA: < 2 g	3	231	Risk Ratio (M‐H, Random, 95% CI)	0.64 [0.42, 0.98]
1.8.2 Dose of 5‐ASA: 2 ‐ 2.9 g	11	1014	Risk Ratio (M‐H, Random, 95% CI)	0.70 [0.53, 0.92]
1.8.3 Dose of 5‐ASA: ≥ 3 g	10	1284	Risk Ratio (M‐H, Random, 95% CI)	0.52 [0.41, 0.66]