Despite the need for a common definition of severe and enduring anorexia nervosa (SE-AN) with the overarching goal to optimize treatments, this definition still is being debated. Therefore, in this study we conducted an in-depth investigation of the history of AN and its clinical outcomes on inpatients with AN to ascertain the eventual “profiles” for individuals with varying durations of the illness (DOI).

We recruited 169 inpatients with AN, grouping them according to DOI: <3 years (short duration, SD-AN); 3–6.99 years (medium duration, MD-AN); and ≥7 years (long duration, LD-AN). We then performed a self-report and interview-based investigation of AN history, clinical data, eating, and general psychopathology, including personality, premorbid traits, stage of change, and quality of life. We measured the clinical outcomes for hospitalization as well.

The majority of the measures did not differ across groups. Those with LD-AN were older and diagnosed mostly with the binge-purging AN subtype, failed more previous AN-related treatments, reported a lower lifetime body mass index, and trended toward a younger age at onset when compared to the other groups. All patients responded equally well to hospitalization, but patients with SD-AN improved less in drive for thinness and body-related concerns.

We did not find the “enduringness” of AN to be a specifier of severity. Hospitalization was effective for those with LD-AN and MD-AN, while interventions for the core cognitive aspects of over-evaluation of body shape should be offered to patients with SD-AN.