A cluster analysis of purging disorder: Validation analyses with eating disorder symptoms, general psychopathology...

To assess the natural grouping of Purging Disorder (PD) patients based on purging symptomatology and to evaluate the derived classes (a) against each other and (b) to a control group on a range of clinical and psychological measures.

Participants included 223 PD women consecutively admitted to a tertiary ED treatment centre and 822 controls. Purging behaviours (self-induced vomiting, laxative and diuretic use) were used as indicators, while the EDI-2 (ED symptoms), the SCL-90-R (general psychopathology), and the TCI-R (personality traits) were used as validators.

Three distinct PD clusters emerged: Cluster 1 (only self-induced vomiting), Cluster 2 (self-induced vomiting and laxative use) and Cluster 3 (all purging methods). Significant differences between Cluster 1 and Cluster 3 were found for the EDI-2 drive for thinness and perfectionism subscales, and the TCI-persistence scale. All clusters differed significantly from the controls on all the EDI-2 and the SCL-90-R scales, but findings for the TCI-R scales were less consistent.

This study adds to a growing literature on the validity and distinctiveness of PD and provides evidence of dimensional symptom differences amongst PD clusters.