Comparison 1. Antibiotics versus placebo for induction of remission.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Failure to induce remission at end of study	7	608	Risk Ratio (M‐H, Random, 95% CI)	0.88 [0.74, 1.06]
1.1.1 Antibiotics + steroids vs placebo + steroids	4	228	Risk Ratio (M‐H, Random, 95% CI)	0.78 [0.51, 1.20]
1.1.2 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	3	330	Risk Ratio (M‐H, Random, 95% CI)	0.96 [0.85, 1.09]
1.1.3 Antibiotics + probiotics + steroids + 5‐ASA vs placebo + probiotics + steroids + 5‐ASA	1	50	Risk Ratio (M‐H, Random, 95% CI)	0.67 [0.37, 1.19]
1.2 Failure to induce remission at 12 months from study end	1	210	Risk Ratio (M‐H, Random, 95% CI)	0.86 [0.74, 0.98]
1.2.1 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	1	210	Risk Ratio (M‐H, Random, 95% CI)	0.86 [0.74, 0.98]
1.3 Failure to induce clinical response at end of study	3	343	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.47, 1.22]
1.3.1 Antibiotics + steroids vs placebo + steroids	1	50	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.39, 1.46]
1.3.2 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	2	293	Risk Ratio (M‐H, Random, 95% CI)	0.72 [0.33, 1.56]
1.4 Failure to induce clinical response at 12 months from study end	2	293	Risk Ratio (M‐H, Random, 95% CI)	0.66 [0.54, 0.80]
1.4.1 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	2	293	Risk Ratio (M‐H, Random, 95% CI)	0.66 [0.54, 0.80]
1.5 Serious adverse events	8	691	Risk Ratio (M‐H, Random, 95% CI)	1.19 [0.38, 3.71]
1.5.1 Antibiotics + steroids vs placebo + steroids	4	228	Risk Ratio (M‐H, Random, 95% CI)	1.19 [0.38, 3.71]
1.5.2 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	4	413	Risk Ratio (M‐H, Random, 95% CI)	Not estimable
1.5.3 Antibiotics + probiotics + steroids + 5‐ASA vs placebo + probiotics + steroids + 5‐ASA	1	50	Risk Ratio (M‐H, Random, 95% CI)	Not estimable
1.6 Withdrawals due to adverse events	8	691	Risk Ratio (M‐H, Random, 95% CI)	2.06 [0.27, 15.72]
1.6.1 Antibiotics + steroids vs placebo + steroids	4	228	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.06, 15.47]
1.6.2 Antibiotics + steroids + 5‐ASA vs placebo + steroids + 5‐ASA	4	413	Risk Ratio (M‐H, Random, 95% CI)	5.00 [0.24, 102.91]
1.6.3 Antibiotics + probiotics + steroids + 5‐ASA vs placebo + probiotics + steroids + 5‐ASA	1	50	Risk Ratio (M‐H, Random, 95% CI)	Not estimable