Assessing Severity in Anorexia Nervosa Using Alternative Criteria to the DSM-5 in a Cross-Sectional Study.

Objective: This study compared overvaluation of weight and shape (OWS), drive for thinness (DT), and their combination (OWS-DT) as alternative severity classifications for anorexia nervosa (AN) to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) severity classification.

Method: 312 AN treatment-seeking outpatients (mean age = 26.8, SD = 10.2, mean body mass index = 17.3, SD = 2.4) were classified using BMI-based DSM-5 criteria (mild/moderate/severe/extreme), OWS (no/yes), DT (no/yes), and OWS-DT combination (neither/one or the other/both). These classifications were evaluated based on associations with clinical and functional severity indicators, including psychiatric comorbidities, psychopathology via the Eating Disorder Examination Questionnaire and the Eating Disorder Inventory, functional impairment via the Eating Disorders Quality-of-Life Questionnaire and Work-and-Social Adjustment Scale, and biological markers.

Results: OWS and DT separately were strongly and positively associated with psychiatric comorbidities, psychopathology, and functional impairment. Severity increased across OWS-DT groups, distinguishing mild (neither), moderate (mainly OWS), and severe (both OWS and DT). DT rarely appeared without OWS. DSM-5 classification alone had limited clinical relevance, primarily reflecting restriction of energy intake. No significant differences emerged across severity classifications for biological markers.

Discussion: Findings offer limited support for DSM-5 severity criteria alone. OWS and DT showed clearer clinical utility, with the OWS-DT combination more effectively identifying severity. A stepwise model-screening for OWS followed by DT assessment-may best capture severity in clinical settings.