Dropout rates in exposure with response prevention for obsessive-compulsive disorder: What do the data really say?

The purposes of this review were to: 1) determine the attrition rates for exposure with response prevention (ERP) for obsessive-compulsive disorder (OCD), 2) compare them to those in other treatments for OCD, and 3) identify predictors of ERP attrition. A systematic literature search of randomized controlled trials for ERP for OCD yielded 21 studies, representing 1400 participants. Attrition data were extracted for individual treatment conditions. The weighted mean dropout rate for ERP was 14.7% (95% CI [11.4%, 18.4%]). This figure was not statistically different from that of comparison conditions (e.g., cognitive therapy; OR=0.67-2.22, all ps>0.15). Only two studies reported refusal rates for ERP (weighted mean=4.0%; 95% CI [0.7%, 9.2%]), which precluded calculation of a reliable refusal rate for ERP. Based on these figures, we estimated an overall attrition rate of 18.7% for ERP. Treatment experience, therapist qualification, and number of treatment sessions did not significantly predict dropout rate. Our review indicates that ERP may have treatment dropout rates similar to other treatments for OCD.