Methodological characteristics and quality of alcohol treatment outcome studies, 1970–98: an expanded evaluation

AIMS: To examine the methodological quality of the research literature examining treatment for alcohol use disorders. DESIGN: In total, 701 studies first reported between 1970 and 1998 were evaluated with a scoring system covering 19 areas of research quality. FINDINGS: Methodological quality improved from a score of 8.2 out of a possible 28.5 in the 1970s, to 10.6 in the 1990s. Strengths included reporting the initial number of participants and conducting follow-ups of 12 months or longer. Although the percentage of studies with adequate power also increased overall, the average statistical power of comparative studies to detect a medium-sized treatment effect was low (0.54). CONCLUSIONS: Areas with room for improvement include: ensuring that follow-up data are collected when respondents are not under the influence of alcohol, testing for differential dropout among treatment groups with respect to participant background characteristics, reporting the number of individuals being treated in the programs from which samples are drawn, noting the reliability and validity of measures used and conducting process analyses to examine potential mechanisms underlying treatment effects.