Adherence to exposure and response prevention as a predictor of improvement in obsessive-compulsive symptom dimensions.

Exposure and response prevention (ERP) is an effective treatment for obsessive compulsive disorder (OCD); yet, improvement rates vary and it is therefore important to examine potential predictors of outcome. The present study examined adherence with ERP homework as a predictor of (a) treatment response across OCD symptom dimensions and (b) reductions in psychological factors implicated in the maintenance of OCD. Fifty adults with OCD received manualized twice-weekly ERP as part of a treatment trial. Results indicated that treatment was effective for all OCD symptom dimensions and that greater adherence with ERP homework predicted post-treatment (but not follow-up) improvements in OCD symptoms pertaining to responsibility for harm, unacceptable obsessional thoughts, and symmetry. Adherence did not predict outcomes for contamination symptoms, however. Adherence also predicted improvement in psychological maintenance factors such as obsessive beliefs and experiential avoidance. Implications of the findings include the importance of emphasizing adherence to homework instructions, as well as the importance of considering OCD symptoms dimensionally as opposed to globally in examining predictors of treatment response.