Meta-analysis of cognitive-behavioral treatment studies for bulimia.

A meta-analysis was performed to systematically assess the effect of cognitive-behavioral treatments for bulimia. To protect against past criticisms of meta-analyses, this study focused on well-defined hypotheses with clearly articulated conceptual foundations. Twenty-six studies of the cognitive-behavioral treatment of bulimia were selected through computer searches. Effect sizes were calculated for changes in behavioral outcome measures (25 independent hypothesis tests) and cognitive-attitudinal outcome measures (17 independent hypothesis tests). Additionally, two effect sizes were generated for within and between group comparisons. The analysis revealed an effect size of average r = 0.69 for behavioral outcome measures (average r = 0.64 for between group and average r = 0.74 for within group) and average r = 0.67 for cognitive-attitudinal outcome measures (average r = 0.64 for between group and average r = 0.69 for within group). Follow-up effect sizes were less favorable; however, the diversity of time spans and outcome measures used to calculate follow-up effect sizes limit their utility. Overall, results suggest that the use of a cognitive-behavioral therapy will result in favorable treatment outcomes and implications for future research are discussed.