Predictors of 1-year treatment outcome in bulimia nervosa

Abstract

We examined predictors of outcome 1 year after completion of a randomized clinical trial assessing the additive efficacy of two forms of exposure with response prevention to a core of cognitive-behavioral therapy (CBT) for bulimia nervosa (BN). One hundred one women who met DSM-III-R criteria for BN, and who completed the clinical trial, were available for follow-up at 1 year. Predictor variables were assessed prospectively and partitioned temporally to reflect lifetime history (including personality), pretreatment clinical status, and posttreatment clinical status. Outcome was based on the frequency of binging and purging in the 3 months before assessment based on carefully constructed lifechart interviews. A series of stepwise logistic regressions were performed to determine independent predictors of 1-year outcome while controlling for treatment received. Demographic variables were unrelated to treatment outcome. A history of obesity was predictive of poor outcome, whereas a history of alcohol dependence decreased the odds of poor outcome. High self-directedness on the Temperament and Character Inventory (TCI) predicted favorable outcome at 1 year, whereas personality disorder symptoms were not predictive. Pretreatment global functioning, bulimia scores on the Eating Disorders Inventory (EDI), and the presence of major depression predicted poor outcome. Posttreatment binging, food restriction, and urges to binge on a cue reactivity assessment predicted poor outcome at 1 year. The character trait of self-directedness is a strong predictor of good outcome for CBT, and methods to enhance this trait may be worthy of investigation. Low global functioning and the presence of major depression at presentation may require additional treatment than focused CBT for BN. Our results argue for treatment goals that include abstinence from binging and restricting and decreases in urges to binge in response to high-risk cues.