Sixty-four trials were included in the review: 45 of naltrexone (5,434 participants), 16 of acamprosate (4,349 participants) and three of naltrexone and acamprosate (1,210 participants).
Acamprosate (g=0.36, 95% CI 0.25 to 0.47; I²=74.8%; 15 trials) showed a statistically significantly larger overall effect size compared to naltrexone (g=0.12, 95% CI 0.05 to 0.18; I²=27.6%; 36 trials) for aggregate abstinence outcomes (p<0.001).
The difference between the two treatments for aggregate heaving drinking outcomes was not statistically significant (p=0.16). Naltrexone showed a statistically significant improvement compared to placebo (g=0.19, 95% CI 0.12 to 0.25; I²=38.2%; 39 trials) and acamprosate did not (I²=32.5%; five trials).
The overall effect size for craving was marginally significantly larger for naltrexone (g=0.144; 26 trials) than acamprosate (g=0.034; nine trials; p=0.075) and was significantly larger for heavy drinking and craving with naltrexone (g=0.18; 42 trials) compared to acamprosate (g=0.041; nine trials; p=0.004).
Meta-regression including all of the moderators identified that for the effects of naltrexone versus placebo, only length of abstinence before treatment was a significant moderator for abstinence outcomes. Length of abstinence before treatment and "other" as the treatment goal were significant moderators for heavy drinking. For acamprosate, meta-regression including all of the moderators identified only detoxification before treatment as a significant moderator.
Other results were reported in the review. There was some evidence of publication bias.