A Meta-Analysis of Retention in Methadone Maintenance by Dose and Dosing Strategy

Objective: To estimate, via meta-analysis, the influence of different methadone dose ranges and dosing strategies on retention rates in methadone maintenance treatment (MMT). Methods: A systematic literature search identified 18 randomized controlled trials (RCTs) evaluating methadone dose and retention. Retention was defined as the percentage of patients remaining in treatment at a specified time point. After initial univariate analyses of retention by Pearson chi-squares, we used multilevel logistic regression to calculate summary odds ratios (ORs) and 95% confidence intervals for the effects of methadone dose (above or below 60 mg/day), flexible vs. fixed dosing strategy, and duration of follow-up. Results: The total number of opioid-dependent participants in the 18 studies was 2831, with 1797 in MMT and 1034 receiving alternative mediations or placebo. Each variable significantly predicted retention with the other variables controlled for. Retention was greater with methadone doses 60 than with doses 60 (OR: 1.74, 95% CI: 1.43-2.11). Similarly, retention was greater with flexible-dose strategies than with fixed-dose strategies (OR: 1.72, 95% CI: 1.41-2.11). Conclusions: Higher doses of methadone and individualization of doses are each independently associated with better retention in MMT.