Drive for thinness provides an alternative, more meaningful, severity indicator than the DSM-5 severity indices for eating disorders.

Our findings question the clinical value of the DSM-5 severity categorisation, and provide initial support for an alternative DT severity approach for AN. HIGHLIGHTS : This study assessed an alternative trans-diagnostic drive for thinness (DT) severity. Category for all eating disorder (ED) sub-types, and then compared this to the Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5) severity indices for EDs. ED symptoms, general psychopathology, personality, and impulsive behaviours were assessed using both classifications in a total of 2,811 female patients diagnosed with EDs. Clinically significant findings were stronger for the DT than the DSM-5 severity category (medium-to-large effect sizes); there was differentiation of the anorexia nervosa (AN) patients into mainly 'low' DT, and bulimia nervosa (BN) spectrum patients into mainly 'high' DT, vs. most patients were clustered in the 'mild-to-moderate' DSM-5 categories. Our findings provide initial support for an alternative trans-diagnostic DT severity category that may be more clinically meaningful than the DSM-5 severity indices for EDs.