Efficacy of indirect dopamine agonists for psychostimulant dependence: a systematic review and meta-analysis of randomized controlled trials

Psychostimulant dependence is characterized by dopamine deficit, which could be reversed with indirect dopamine agonists (IDAs). A systematic review and meta-analysis of randomized, parallel-group, placebo-controlled clinical trials assessing the efficacy of IDAs in psychostimulant-dependent individuals were conducted. The study outcomes were psychostimulant abstinence, assessed by means of urinalysis, and retention in treatment. Risk of bias was determined using a Cochrane Collaboration instrument. Twenty-nine studies fulfilled the inclusion criteria, involving 2,467 participants. Compared with placebo, IDAs increased psychostimulant abstinence (standardized mean difference = 0.20; 95% confidence interval, 0.06-0.35; p = .005) but did not increase retention in treatment. Efficacy was larger in comorbid heroin-dependent individuals and was positively related with treatment length. No study was considered fully free of bias. IDAs appear to be efficacious for reducing psychostimulant use but did not improve retention. Efforts should be undertaken to reduce the risk of bias of clinical trials with psychostimulant-dependent individuals.