The double battle: comparing the six-year course of obsessive-compulsive disorder with and without comorbid eating disorder

Background: Eating disorders (ED) are more prevalent in individuals with obsessive-compulsive disorder (OCD), and their co-occurrence is associated with higher symptom-severity, increased risk of additional comorbidities, including depression, and poorer treatment outcomes. However, little is known about the long-term course of OCD in patients with versus without comorbid ED. This study investigated the 6-year clinical course of OCD symptom-severity in patients with (OCD + ED) and without (OCD-ED) lifetime ED. Methods: Within the Netherlands OCD Association (NOCDA) cohort, 382 participants with a DSM-IV OCD diagnosis were classified as OCD + ED (n = 46; 91 % women; mean age 34.5) or OCD-ED (n = 336; 52 % women; mean age 36.6). Lifetime ED diagnoses included anorexia nervosa (39 %) and binge-eating disorder (37 %). OCD and ED diagnoses, symptom severity, and clinical/demographic variables were assessed at baseline and after two, four, and six years. Linear mixed-effects models were used to examine group differences in OCD symptom trajectories. Results: OCD + ED participants showed higher baseline obsessive-compulsive, depressive, and anxiety symptoms, and more comorbid posttraumatic stress disorder than OCD-ED patients. Despite these differences, both groups followed a comparable 6-year course of OCD symptom severity, with no significant between-group differences in symptom reduction. Y-BOCS scores decreased by 4.17 points in OCD-ED and 5.24 in OCD + ED; PADUA scores declined by 13.68 and 15.65 points, respectively. Conclusion: While OCD + ED patients showed a more significant clinical burden, comorbid ED did not significantly moderate long-term OCD symptom trajectories, suggesting a need for more intensive and/or longer treatment. The relatively small size of the OCD + ED group may be considered a limitation.