Mediation of symptom changes during inpatient treatment for eating disorders: the role of obsessive-compulsive features.

The present study examined the relative contributions of changes in obsessive-compulsive symptoms among eating-disorder patients with (n = 254) and without (n = 254) obsessive-compulsive disorder (OCD) to eating-disorder symptom improvement observed with inpatient treatment. Consistent with hypothesis, multilevel mediation analyses revealed that improvements in OCD symptoms over time accounted for significant variance in the improvements in eating-disorder symptoms over time, with stronger mediation evident among eating-disorder patients with comorbid OCD (percent mediated; P(M) = 22.5%) compared to those without OCD (P(M) = 12.2%). However, decreases in eating-disorder symptoms over time fully mediated improvements in OCD symptoms over time, and this mediated pathway did not vary substantially as a function of comorbid OCD status. The theoretical and treatment implications of these findings for conceptualizing the relationship between eating disorders and OCD are discussed.