Meta-analysis of CBT for Bulimia Nervosa: Investigating the Effects Using DSM-III-R and DSM-IV Criteria

This meta-analysis reports the effects of cognitive-behavioural treatment (CBT) on bulimia nervosa as defined by the DSM-III-R or DSM-IV criteria. In a previous meta-analysis, 26 studies were included using less strict diagnostic criteria for inclusion. The present meta-analysis only included randomized controlled studies fulfilling the DSM-III-R or DSM-IV criteria. Computer searches in MedLine, PsychLIT and references cited herein resulted in a large number articles, of which only seven fulfilled the criteria for inclusion. Effect sizes for binge eating and purging frequency were estimated using both between-group (treatment vs control) and within-group (pre- vs post-treatment) comparisons. The combined within-group effect size for binge eating was r = 0.55 ( d = 1.32) and for purging r = 0.61 ( d = 1.54). The corresponding combined effects for the between-group comparisons were r = 0.23 ( d = 0.47) and r = 0.28 ( d = 0.58), respectively. The combined probabilities for frequency of purging in between- and within-group comparisons were p = 0.00001 and p = 0.00000001, respectively. Although the number of studies included in the meta-analysis was limited, the obtained results are in line with the findings of the previous meta-analysis, and support the efficacy of CBT for the treatment of bulimia nervosa. This suggestion is also supported by the fact that in all the studies except one, comparison groups had received other active treatments.