Comparison 1. One infusion of natalizumab (300 mg or 3 mg/kg) versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Failure to induce remission at 2 weeks	3	1132	Risk Ratio (M‐H, Fixed, 95% CI)	0.94 [0.89, 0.98]
2 Failure to induce remission at 4 weeks	3	1611	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.86, 0.96]
3 Failure to induce clinical response at 2 weeks	2	1102	Risk Ratio (M‐H, Random, 95% CI)	0.82 [0.66, 1.01]
4 Failure to induce clinical response at 4 weeks	3	1611	Risk Ratio (M‐H, Random, 95% CI)	0.78 [0.66, 0.92]
5 Change in CDAI from baseline to 4 weeks	1	507	Mean Difference (IV, Fixed, 95% CI)	‐32.9 [‐47.85, ‐17.95]
6 Adverse events	1	131	Risk Ratio (M‐H, Fixed, 95% CI)	0.91 [0.75, 1.09]
7 Withdrawal due to adverse events	1	131	Risk Ratio (M‐H, Fixed, 95% CI)	0.46 [0.04, 4.98]
8 Serious adverse events up to week 12	1	131	Risk Ratio (M‐H, Fixed, 95% CI)	0.93 [0.34, 2.49]