Early compliance and other factors predicting outcome of exposure for obsessive-compulsive disorder.

BACKGROUND Identifying predictors of treatment outcome can suggest ways to improve treatment delivery and understanding of its mechanism of action. METHOD Predictors of treatment outcome were sought among 46 out-patients with obsessive-compulsive disorder who completed a nine-week randomised controlled trial of two forms of exposure therapy with ritual prevention. RESULTS In both exposure conditions the best predictor of good outcome at the end of treatment (week 9) and of follow-up (week 32) was early compliance in doing exposure homework within a week of starting treatment. A weaker predictor of good outcome at follow-up was within-session reduction in anxiety from weeks 0 to 4. CONCLUSION The strongest and most consistent predictor of better outcome to weeks 9 and 32 was compliance with exposure and ritual prevention in the first week of treatment.