Naltrexone, a relapse prevention maintenance treatment of alcohol dependence: a meta-analysis of randomized controlled trials

CRD COMMENTARY: The aims were stated and the inclusion criteria were defined in terms of the study design, intervention, participants and outcome. Several relevant sources of literature were searched and attempts were made to locate unpublished material. By restricting eligible studies to those published in the English language, other relevant articles might have been omitted. Duplicate articles were removed but the methods used to select the studies were not described. Eligible studies were restricted to RCTs, and a formal validity assessment was undertaken using defined criteria. Only one reviewer assessed validity and extracted the data. Relevant data and the validity scores of individual studies were tabulated. Statistical heterogeneity was assessed and reported. The differences between the individual studies in terms of the characteristics of the populations and the definitions of the outcomes, were described. The data were combined in a meta-analysis using both a fixed-effect and random-effects model. Despite evidence of statistical heterogeneity for the primary outcome of 'relapse rate', the authors incorrectly supported the use of a random-effects model and did not investigate potential causes of this heterogeneity. Without an exploration of the potential causes of heterogeneity among the studies with respect to relapse rates, it is not possible to determine the circumstances in which naltrexone is of benefit.