Validation of the Interpersonal Relationships in Eating Disorders (IR-ED) Scale in an Eating Disorder Sample

Abstract

Objective: Interpersonal problems have been identified as a plausible mechanism underlying the onset and maintenance of eating disorders. The Interpersonal Relationships in Eating Disorders (IR-ED) scale is the first eating disorders-specific measure of interpersonal problems, which was developed in a nonclinical sample. The aims of the current study were to (a) confirm the factor structure of the IR-ED within a large clinical sample, (b) investigate measurement invariance of the IR-ED across nonclinical and clinical samples, (c) examine the convergent validity of the IR-ED using a generic measure of interpersonal problems, and (d) investigate the incremental clinical utility of the IR-ED in uniquely predicting eating disorder symptomatology. Method: Treatment-seeking individuals (N = 437) completed the IR-ED at their initial assessment appointment at a specialist eating disorder outpatient service. Results: A multiple-group confirmatory factor analysis supported an invariant bifactor structure comprising a general interpersonal problems factor and two group factors—Avoidance of Body Evaluation and Food-Related Interpersonal Tension. Convergent validity was demonstrated by a large, statistically significant correlation with a generic measure of interpersonal problems (r = 0.62, p < 0.001). A series of structural equation models further revealed unique incremental predictive utility of the IR-ED for eating disorder symptomatology. Discussion: The IR-ED has strong psychometric properties and may prove beneficial in the assessment, formulation, and treatment of eating-specific interpersonal problems among patients with eating disorders.