Objective
Evidence suggests that eating disorder subtypes reflecting under‐controlled, over‐controlled, and low psychopathology personality traits constitute reliable phenotypes that differentiate treatment response. This study is the first to use statistical analyses to identify these subtypes within treatment‐seeking individuals with bulimia nervosa (BN) and to use these statistically derived clusters to predict clinical outcomes.
Methods
Using variables from the Dimensional Assessment of Personality Pathology‐Basic Questionnaire, K‐means cluster analyses identified under‐controlled, over‐controlled, and low psychopathology subtypes within BN patients (n = 80) enrolled in a treatment trial. Generalized linear models examined the impact of personality subtypes on Eating Disorder Examination global score, binge eating frequency, and purging frequency cross‐sectionally at baseline and longitudinally at end of treatment (EOT) and follow‐up. In the longitudinal models, secondary analyses were conducted to examine personality subtype as a potential moderator of response to Cognitive Behavioral Therapy‐Enhanced (CBT‐E) or Integrative Cognitive‐Affective Therapy for BN (ICAT‐BN).
Results
There were no baseline clinical differences between groups. In the longitudinal models, personality subtype predicted binge eating (p = 0.03) and purging (p = 0.01) frequency at EOT and binge eating frequency at follow‐up (p = 0.045). The over‐controlled group demonstrated the best outcomes on these variables. In secondary analyses, there was a treatment by subtype interaction for purging at follow‐up (p = 0.04), which indicated a superiority of CBT‐E over ICAT‐BN for reducing purging among the over‐controlled group.
Discussion
Empirically derived personality subtyping appears to be a valid classification system with potential to guide eating disorder treatment decisions. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:506–514)