Eating disorders and concurrent psychopathology: a reconceptualisation of clinical need through Rasch analysis.

Therapies for anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED) and eating disorder not otherwise specified (EDNOS) take as their focus, perhaps of necessity, the eating disorder symptomatology. However, there is increasing evidence of comorbidity of psychopathological mechanisms (e.g. perfectionism, depression) with eating disorders which, left untreated, may diminish any therapeutic effects. Thus identifying the extent of comorbidity in an eating disorder population and assessing the relationship between psychopathological mechanisms and the eating disorder is important. Rasch analysis was applied to the findings from questionnaires (EDI-2; SCL90-R) completed by 105 female patients referred to an eating disorder unit. General psychopathology was found to be more indicative of 'caseness' than eating disorder psychopathology. In particular, interpersonal sensitivity, depression and mild interpersonal aspects of psychoticism emerged as important factors across eating disorders. The comorbidity of psychopathological mechanisms needs to be given consideration in the successful treatment of eating disorders.