The impact of symptom dimensions on outcome for exposure and ritual prevention therapy in obsessive-compulsive disorder.

OBJECTIVE Obsessive-compulsive disorder (OCD) is a severe condition with varied symptom presentations. The behavioral treatment with the most empirical support is exposure and ritual prevention (EX/RP). This study examined the impact of symptom dimensions on EX/RP outcomes in OCD patients. METHOD The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) was used to determine primary symptoms for each participant. An exploratory factor analysis (EFA) of 238 patients identified five dimensions: contamination/cleaning, doubts about harm/checking, hoarding, symmetry/ordering, and unacceptable/taboo thoughts (including religious/moral and somatic obsessions among others). A linear regression was conducted on those who had received EX/RP (n=87) to examine whether scores on the five symptom dimensions predicted post-treatment Y-BOCS scores, accounting for pre-treatment Y-BOCS scores. RESULTS The average reduction in Y-BOCS score was 43.0%, however the regression indicated that unacceptable/taboo thoughts (β=.27, p=.02) and hoarding dimensions (β=.23, p=.04) were associated with significantly poorer EX/RP treatment outcomes. Specifically, patients endorsing religious/moral obsessions, somatic concerns, and hoarding obsessions showed significantly smaller reductions in Y-BOCS severity scores. CONCLUSIONS EX/RP was effective for all symptom dimensions, however it was less effective for unacceptable/taboo thoughts and hoarding than for other dimensions. Clinical implications and directions for research are discussed.