Evaluation of the DSM-5 severity ratings for anorexia nervosa in a clinical sample.

We examined the validity and utility of the DSM-5 severity ratings for anorexia nervosa (AN) in a clinical (treatment-seeking) sample (N = 273; 95.6% women). Participants classified with mild, moderate, severe, and extreme severity of AN based on their measured body mass index, differed significantly from each other in eating disorder features, putative maintenance factors, and illness-specific functional impairment (medium effect sizes). However, they were statistically indistinguishable in psychiatric-disorder comorbidity and distress, demographics, and age-of-AN onset. The implications of our findings, providing limited support for the DSM-5 severity ratings for AN, and directions for future research are outlined.