Have personality disorders been overdiagnosed among eating disorder patients?

There is persuasive evidence for a relationship between eating disorders (EDs) and personality disorders (PDs). Research studies over the last three decades have used various tools to explore PDs in EDs with differing results. We investigated PDs derived from an interview--the International Personality Disorder Examination.

132 female inpatients with restrictive anorexia nervosa (AN-R), binge-purging AN, bulimia nervosa (BN) and ED not otherwise specified were interviewed. MANCOVA was used to test for differences in dimensional PD scores for the ED diagnostic and behavioural groups.

Twenty-one percent of patients had a definite DSM-IV PD diagnosis and 37% of patients had ≥1 definite or probable DSM-IV PD diagnoses. Cluster C PDs were most commonly found [avoidant (25%), obsessive-compulsive (9%), dependent (2%)], followed by cluster B PDs [borderline (13%), histrionic (2%)]. Comparison of PD dimensional scores revealed significantly lower PD scores for borderline PD in AN-R when compared to the other diagnostic groups; and significantly higher scores for histrionic, narcissistic, antisocial, and not otherwise specified PDs for BN when compared to the other diagnostic groups. Self-induced vomiting was the only behaviour significantly associated with any PD dimensional scores (borderline and narcissistic).

Assessment of PDs using a highly structured interview administered by trained interviewers results in less PD diagnoses compared with previous studies of inpatients with an ED. Avoidance is the most common PD and those patients who induce vomiting are more likely to have borderline features.