Abstract Response to psychological treatment for Obsessive-Compulsive Disorder (OCD)
varies, and dropout and relapse rates remain troubling. However, while studies examining symptom
reductions are favourable, outcomes are less encouraging when outcome is defined in terms
of clinically significant change. Moreover, there is little understanding of what predicts treatment
outcome. This study examined demographic, symptomatic and cognitive predictors of
outcome in 79 participants undertaking individualised cognitive-behavioural therapy for OCD.
After investigating differences between treatment completers and non-completers, we examined
treatment response as defined by post-treatment symptom severity and clinically reliable
change, as well as predictors of treatment response. Completers were less likely to present
with co-morbidity. The treatment was highly efficacious irrespective of whether completer
or intention-to-treat analysis was undertaken, with 58% of treatment completers considered
‘‘recovered’’ at post-treatment. Lower pre-treatment levels of OCD symptoms and greater
perfectionism/intolerance of uncertainty were the best unique predictors of OCD severity outcomes
at post-treatment. Changes in obsessional beliefs were associated with symptomatic
change, although only perfectionism/intolerance of uncertainty was a significant unique predictor
of post-treatment change. Recovery status was predicted only by pre-treatment OCD
severity. In helping to identify those at risk for poorer outcomes, such research can lead to the
development of more effective interventions.