A review of purging disorder through meta-analysis

Although a growing body of research has examined Purging Disorder (PD), there remains a lack of conclusive evidence regarding the diagnostic validity of PD. This meta-analysis compared PD to DSM-5 eating disorders (i.e., Anorexia Nervosa [AN], Bulimia Nervosa [BN], and Binge Eating Disorder [BED]) and controls. A comprehensive literature search identified 38 eligible studies. Group differences on indicators of course of illness and both general and eating psychopathology were assessed using standardized effect sizes. Results supported the conceptualization of PD as a clinically significant eating disorder, but findings were less clear regarding its distinctiveness from other eating disorder diagnoses. More specifically, PD significantly differed from BN and BED in natural course of illness (g = .40 -.54), and PD significantly differed from AN in treatment outcome (g = .27), with PD characterized by a better prognosis. Overall, PD was more similar to AN and BED on many dimensional measures of general and eating-related psychopathology, though PD was less severe than BN in most of these domains. PD, BN, and BED groups also evidenced similar frequencies of subjective binge episodes (SBEs), yet PD evidenced less frequent SBEs than AN. There is a clear need for future studies of PD to assess validators that have not been reported comprehensively in the literature, such as mortality, medical morbidity, and course of illness. Additionally, empirical classification studies are needed to inform future classifications of PD, particularly with regard to categorical differences between PD and other eating disorders.