Integrating "Lumpers" versus "Splitters" Perspectives: Toward a Hierarchical Dimensional Taxonomy of Eating Disorders from Clinician Ratings.

This study describes a hierarchical dimensional model of eating-disorder (ED) classification based on the Hierarchical Taxonomy of Psychopathology (HiTOP). Participants were community-recruited adults with an ED (=252; 81.9% female). We used a modified version of Goldberg's (2006) method, which involved sequentially extracting latent factors using exploratory structural equation modeling, resulting in a 10-factor hierarchical-dimensional model. Dimensions predicted 92.4% and 58.7% of the variance in recovery outcomes at six-month and one-year, respectively. Compared to other illness indicators (e.g., diagnoses, dimensional ED impairment scores, weight/shape overvaluation, and ED severity specifiers), hierarchical dimensions predicted .88 to 334 times more variance in ED behaviors at baseline and 1.95 to 80.8 times more variance in psychiatric impairment at one-year follow-up. Results suggest that reducing within-disorder heterogeneity for EDs within the broader context of internalizing symptoms provides a powerful framework from which to predict outcomes and understand symptoms experienced by those with EDs.