Prognostic significance of two sub-categorization methods for the treatment of binge eating disorder: Negative affect and overvaluation predict, but do not moderate, specific outcomes

Given the absence of known predictors and moderators for binge eating disorder (BED) treatment outcome and recent findings regarding meaningful sub-categorizations of BED patients, we tested the predictive validity of two subtyping methods. Seventy-five overweight patients with BED who participated in a randomized clinical trial of guided self-help treatments (cognitive-behavioral therapy (CBTgsh) and behavioral weight loss (BWLgsh)) were categorized in two ways. First, a cluster analytic approach yielded dietary-negative affect (29%) and pure dietary (71%) subtypes. Second, research conventions for categorizing patients based upon shape or weight self-evaluation yielded clinical overvaluation (51%) and subclinical overvaluation (49%) subtypes. At the end of treatment, participants subtyped as dietary-negative affect reported more frequent binge episodes compared to the pure dietary subtype, and those with clinical overvaluation reported greater eating disorder psychopathology compared to the subclinical overvaluation group. Neither method predicted binge remission, depressive symptoms, or weight loss. Neither sub-categorization moderated the effects of guided self-help CBT and BWL treatments on any BED outcomes, suggesting that these two specific treatments perform comparably across BED subtypes. In conclusion, dietary-negative affect subtyping and overvaluation subtyping each predicted, but did not moderate, specific and important dimensions of BED treatment outcome.