Towards the definition of an 'eating disorder'

This dissertation is concerned with the diagnosis and classification of clinical eating disorders such as anorexia nervosa and bulimia nervosa. There were four overarching aims. The first was to describe the clinical characteristics of patients with the neglected DSM-FV eating disorder diagnosis "eating disorder NOS" and compare them with those of patients with bulimia nervosa. It was found that the two groups were remarkably similar. The second was to examine how the classificatory problems associated with this diagnosis might be solved. Three solutions were proposed and the clinical utility of two of them examined. It was concluded that the best interim solution was to broaden the diagnostic criteria for anorexia nervosa and bulimia nervosa and re-label the remaining cases of eating disorder NOS as either binge eating disorder or as a new eating disorder diagnosis. The third aim was to derive an operational definition of what constitutes an "eating disorder" This involved developing an interview-based measure of functional impairment secondary to eating disorder features and administering it to a large sample of people exhibiting the full range of eating disorder psychopathology. Multivariate statistics identified specific severity levels on five eating disorder features that were strongly associated with the presence of a clinically significant level of impairment. These eating disorder features were: the pursuit of strict dietary rules, objective bulimic episodes, purging episodes, dissatisfaction with shape and weight, and over-concern with maintaining strict control over eating. The presence of two or more of these features above the identified thresholds was most predictive of a clinically significant level of impairment. Thus, an impairment-based, transdiagnostic, provisional operational definition of an eating disorder was derived. The fourth aim was to develop a clinically useful, easily administered measure of psychosocial impairment secondary to eating disorder features. Such an instrument was created. Studies of its psychometric properties, reliability, validity and sensitivity to change all supported its use. Certain of the research strategies used in this dissertation could be usefully applied to other psychiatric disorders

Towards the definition of an 'eating disorder'

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