Measurement Invariance Widely Holds for the Yale-Brown Obsessive Compulsive Scale

The clinician-rated Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is a widely used assessment tool for obsessive-compulsive disorder (OCD). However, the measurement invariance (MI) properties of the Y-BOCS, a prerequisite for group or time point comparisons in clinical research, have received little attention in previous studies. In this study, we aim to comprehensively investigate the factor structure and MI of the Y-BOCS severity rating and its symptom checklist, utilizing a large sample of OCD patients (N = 1,066). Our analysis considers various MI covariates, including time (pre- and post-therapy), severity, comorbidity, previous treatments, and demographics. Overall, the majority of tests conducted on the Y-BOCS severity rating and its symptom checklist revealed no substantial issues with MI, reinforcing the validity of the Y-BOCS for comparative clinical research. Specifically, we discuss a three-factor model for the severity rating, contrasting with a two-factor model for obsessions and compulsions when excluding the resistance items. Notably, our findings underscore the advantages and validity of employing latent factors rather than sum scores to model OCD severity and symptoms.