Ecological momentary assessment of purging disorder

Purging Disorder (PD) is characterized by purging after normal or small amounts of food among individuals who are not underweight. Several studies indicate that PD is associated with distress and impairment, underscoring the need for intervention. However, little is known about factors that trigger and maintain purging in PD. This study examined antecedents and consequences of purging using Ecological Momentary Assessment (EMA), a design that involved repeated assessments of current psychological states in participants' natural environments. Women with PD (N = 24) were recruited from the community to make multiple daily ratings of affect, shape/weight concerns, violation of dietary rules, and stomach discomfort using random-, interval-, and event-contingent recordings over a two-week period. Multilevel model analyses were used to examine between-day differences (purge versus non-purge day) and within-day changes in psychological variables relative to purging behavior. Results supported study hypotheses that negative affect and shape/weight concerns would be higher and positive affect would be lower on days when participants purged compared to days they did not purge. In addition, antecedent analyses supported within-day increases in negative affect, shape/weight concerns, and stomach discomfort prior to purging; however, only changes in positive affect and shape/weight concerns on purge days differed from naturally-occurring changes observed on non-purge days. For consequence analyses, negative affect, shape/weight concerns, and stomach discomfort decreased following purging on purge days, and trajectories of change were significantly different from non-purge days. Finally, exploratory analyses suggested that lower levels of impulsivity enhanced associations between antecedent affect and purging. These data are crucial to understand why women with PD purge after consuming normal or small amounts of food and may point to specific targets for the development of effective interventions.