Comparing definitions of purging disorder on point prevalence and associations with external validators

We varied two defining features of Purging Disorder (PD): breadth of "purging" behaviors (purging only [narrow] vs. purging and nonpurging [broad]) and minimum behavioral frequency (once vs. twice per week) to examine their impact on syndrome validity.

Survey data from 1736 women and 755 men were used for analyses.

PD point prevalence was higher in women versus men, and prevalence was lowest for the narrow definition requiring purging twice per week. The narrow definition was associated with significant psychosocial impairment and increased effect sizes in validation analyses. Changing minimum behavioral frequencies did not impact associations with external validators.

A broad definition of PD that included any compensatory behavior reduced distinctions between PD and normality. Reducing minimum frequency to once per week did not reduce homogeneity or evidence of syndrome severity. Purging once per week may represent the optimal starting point in defining the central behavioral feature of PD.