Comparison 1. naltrexone versus placebo or no pharmacological treatments.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 retention in treatment	2	83	Risk Ratio (M‐H, Fixed, 95% CI)	1.18 [0.72, 1.91]
2 retention and abstinence, all patients	6	393	Risk Ratio (M‐H, Random, 95% CI)	1.43 [0.72, 2.82]
3 retention and abstinence, patients forced to abstinence	3	230	Risk Ratio (M‐H, Fixed, 95% CI)	2.93 [1.66, 5.18]
4 abstinence	4	143	Risk Ratio (M‐H, Random, 95% CI)	1.39 [0.61, 3.17]
5 abstinence at follow up	3	116	Risk Ratio (M‐H, Fixed, 95% CI)	1.28 [0.80, 2.05]
6 side effects	4	159	Risk Ratio (M‐H, Random, 95% CI)	1.29 [0.54, 3.11]
7 re‐incarceration	2	86	Risk Ratio (M‐H, Fixed, 95% CI)	0.47 [0.26, 0.84]