Impact of altering DSM-IV criteria for anorexia and bulimia nervosa on the base rates of eating disorder diagnoses.

The diagnostic criteria used to define eating disorders have been the focus of debate for many years. The primary aim of this study was to evaluate the impact of altering DSM-IV diagnostic criteria upon the base rates of anorexia nervosa (AN), bulimia nervosa (BN) and eating disorder not otherwise specified (EDNOS). Five controversial criteria were systematically modified and the impact of these changes on base rates of full-syndrome and partial-syndrome eating disorders was assessed in 193 patients referred to two specialty eating disorder clinics. Modification of a single criterion resulted in relatively small changes in base rates of AN and BN, whereas modification of the two severity criteria led to more substantial changes. These findings have significant implications for future modifications of the DSM classification.