Evaluation of the DSM-5 Severity Specifier for Bulimia Nervosa in Treatment-Seeking Youth

A new severity specifier for bulimia nervosa (BN), based on the frequency of inappropriate weight compensatory behaviours (e.g., laxative misuse, self-induced vomiting, fasting, diuretic misuse, and excessive exercise), has been added to the most recent (fifth) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a means of addressing variability and heterogeneity in the severity of the disorder. While existing research provides support for the DSM-5 severity specifier for BN in adult patients, evidence for its validity and clinical utility in youth is currently lacking. To address this gap, data from 272 treatment-seeking adolescents with DSM-5 BN (94.2% female, M _age = 15.3 years, SD 1.7) were analysed to examine whether these patients, sub-grouped based on the DSM-5 severity definitions, would show meaningful differences in a broad range of clinical variables and demographic and physical characteristics. Analyses revealed that participants categorized with mild, moderate, severe, and extreme severity of BN significantly differed from each other in 15 variables regarding eating disorder pathological features and putative maintenance factors (i.e., core low self-esteem, perfectionism, social appearance anxiety, body surveillance, and mood intolerance), health-related quality of life and comorbid psychiatric (i.e., affective and anxiety) disorders (large effect sizes). Between-group differences in demographics, body mass index, or age-of-BN onset were not observed. Collectively, our findings provide support for the utility of the frequency of inappropriate weight compensatory behaviours as a severity indicator for BN and suggest that age-at-onset of BN is probably more disorder- than severity-dependent. Implications for future research are outlined.