Staging anorexia nervosa: conceptualizing illness severity.

In recent years, there has been increasing attention to the conceptualization of anorexia nervosa (AN) and its diagnostic criteria. While varying levels of severity within the illness category of AN have long been appreciated, neither a precise definition of severity nor an empirical examination of severity in AN has been undertaken. The aim of this article is to review the current state of knowledge on illness severity and to propose a theoretical model for the definition and conceptualization of severity in AN. AN is associated with significant medical morbidity which is related to the 'severity' of presentation on such markers as body mass index, eating and purging behaviours. The development of a functional staging system, based on symptom severity, is indicated for reasons similar to those cited by the cancer lobby. Improving case management and making appropriate treatment recommendations have been the primary purpose of staging in other fields, and might also apply to AN. Such a standardized staging system could potentially ease communication between treatment settings, and increase the specificity and comparability of research findings in the field of AN.