Incompleteness as a clinical characteristic and predictor of treatment outcome in obsessive-compulsive disorder

Incompleteness, that is, a feeling that things are “not just right”, is an understudied symptom of obsessive-compulsive disorder (OCD). We used data from 167 adult individuals with OCD who received internet-delivered cognitive behaviour therapy (ICBT) to examine how incompleteness was associated with clinical characteristics and treatment outcomes. Incompleteness was assessed using the Obsessive-Compulsive Trait Core Dimensions Questionnaire (OCTCDQ). Results showed that the proposed two-factor structure of the OCTCDQ had adequate model/data fit in the present sample. Incompleteness was positively associated with baseline symmetry/ordering symptoms (β = 0.52, [95% CI 0.48 to 0.56], p < 0.001), psychiatric comorbidity (β = 0.23, [95% CI 0.21 to 0.25], p < 0.05) and self-reported symptom severity (Y-BOCS-SR β = 0.35, [95% CI 0.27 to 0.43], p < 0.001; OCI-R β = 0.46, [95% CI 0.34 to 0.59], p < 0.001). Results showed that higher degree of incompleteness predicted a worse treatment outcome on clinician-rated, but not self-rated, measures of symptom severity. Participants with a high (vs. low) degree of incompleteness were less likely to be classified as responders (39% vs. 52%) and remitters (10% vs. 34%) at post-treatment. The results suggest that incompleteness is a clinically relevant feature of OCD, which may require treatment adaptations for some patients but more research is needed to confirm that the findings are not entirely due to measurement error.