Multiple measures of rapid response as predictors of remission in cognitive behavior therapy for bulimia nervosa

Bulimia nervosa (BN) treatment studies consistently observe that substantial reductions in purging frequency after four weeks of treatment predict outcome. Although baseline levels of other variables have been compared to change in purging, measures of early change in other domains have not been examined. This study aimed to compare percentage change in purging, depression, and cognitive eating disorder (ED) symptoms for associations with BN remission post-treatment and at six months follow-up. Data from N = 43 patients with BN in a clinical trial comparing the broad and focused versions of enhanced cognitive behavior therapy (CBT-E; Fairburn, 2008) were utilized. Measures included self-reported purging frequency, Beck Depression Inventory (BDI) score, and a mean of items from the Eating Disorder Inventory Body Dissatisfaction and Drive for Thinness subscales. Results indicated that both percentage change in purging frequency and percentage change in BDI score at week four/session eight were significantly associated with remission at termination. The optimal cutoffs for purging change and BDI score change were 65% decrease and 25% decrease respectively. Only change in BDI score at week four significantly predicted remission at six-month follow-up. These data suggest that change in depressive symptoms may be as important as ED symptom change to predict outcome in some groups.