Item-by-item factor analysis of the Yale-Brown Obsessive Compulsive Scale Symptom Checklist.

Clinical subtypes of obsessive-compulsive disorder may have differing pathophysiological mechanisms and treatment outcomes. The subtypes identified by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) Symptom Checklist, clustered by clinical consensus, have never been subject to statistical validation. A factor analysis using a sample of 160 patients with OCD was conducted to determine whether factor analytically derived categories are identical to extant clinically determined categories. Our analysis revealed that the contamination subtype of the Y-BOCS Symptom Checklist contains two distinct subgroups: one relating to discomfort and the other to fear of harm. If replicated on a larger scale, the finding of new subtype groupings would have important implications for future research in obsessive-compulsive disorder.