Importance of multiple purging methods in the classification of eating disorder subtypes.

OBJECTIVE To examine two assumptions implicit in the subtyping of eating disorders: (1) purging behaviors are interchangeable, and (2) a primary distinction exists between the presence vs. absence of any means of purging. METHOD Data from a longitudinal study of health and eating patterns were used to compare women who reported self-induced vomiting, laxative abuse, or their combination. Further comparisons were made among women who used multiple purging methods (MP), a single purging method (SP), and randomly selected controls who never purged. RESULTS Vomiting and laxative abuse were associated with similar levels of eating pathology whereas their combination was associated with greater eating pathology. MP women reported significantly greater eating pathology compared to SP women who reported significantly greater eating pathology compared to controls. Differences were maintained at 10-year follow-up. CONCLUSION Purging behaviors may be interchangeable but the use of multiple purging methods is associated with greater severity over time.