Testing the DSM-5 severity indicator for bulimia nervosa in a treatment-seeking sample

Purpose: This study tested the new DSM-5 severity criterion for bulimia nervosa (BN) based on the frequency of inappropriate weight compensatory behaviors in a treatment-seeking sample. Methods: Participants were 345 adults with DSM-5 BN presenting for treatment. They were sub-grouped based on DSM-5 severity levels and compared on a range of variables of clinical interest and demographics. Results: Based on DSM-5 severity definitions, 27.2 % of the sample was categorized with mild, 26.1 % with moderate, 24.9 % with severe, and 21.8 % with extreme severity of BN. Analyses revealed that the four (mild, moderate, severe, and extreme) severity groups of BN significantly differed from each other in eating disordered and body-related attitudes and behaviors, factors involved in the maintenance process of the disorder, comorbid psychiatric disorders, psychological distress, and psychosocial impairment (medium-to-large effect sizes). No significant between-group differences were observed in demographics, body mass index, or at the age when BN first occurred, lending some credence to recent suggestions that age-at-onset of BN may be more a disorder- than a severity-dependent variable. Conclusions: Collectively, our findings provide support for the severity indicator for BN introduced in the DSM-5 as a means of addressing heterogeneity and variability in the severity of the disorder.