Severity levels of anorexia nervosa and atypical anorexia nervosa in a Korean cohort.

Objective: Despite its potential for informing tailored treatments, the severity of eating disorders (EDs) lacks clear conceptualisation. The present retrospective cohort study examined the clinical validity and utility of severity specifiers for anorexia nervosa (AN) and atypical AN in a Korean population.

Method: Data from 696 Korean outpatients with AN or atypical AN were analysed. Severity criteria for AN from the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and the Medical Emergencies in Eating Disorders (MEED) guidance were used. Severity criteria applied for atypical AN were the frequency of intermittent fasting (ED Diagnostic Scale item 17), Eating Disorder Examination Questionnaire global scores, and the degree of weight suppression.

Results: Prevalence of extreme cases of AN in our cohort was higher than in Western populations in previous studies. MEED guidance further subclassified extreme AN, revealing distinct psychopathological profiles across severity levels. The proposed severity classification for atypical AN based on the weight loss behaviour of intermittent fasting showed merit.

Conclusions: These findings suggest a potential need for a more nuanced AN severity classification that better represents severe medical aspects and encompasses cultural and ethnic diversities. In atypical AN, there is a need to examine severity indices measuring pathological behaviours.