Measurement fidelity of clinical assessment methods in a global study on identifying reproducible brain signatures of obsessive-compulsive disorder.

To describe the steps of ensuring measurement fidelity of core clinical measures in a five-country study on brain signatures of obsessive-compulsive disorder (OCD). We collected data using standardized instruments, which included the Yale-Brown Obsessive-Compulsive Scale (YBOCS), the Dimensional YBOCS (DYBOCS), the Brown Assessment of Beliefs Scale (BABS), the 17-item Hamilton Depression Scale (HAM-D), the Hamilton Anxiety Scale (HAM-A), and the Structured Clinical Interview for DSM-5 (SCID). Steps to ensure measurement fidelity included translating instruments, developing a clinical decision manual, and continuing reliability training with 11-13 transcripts of each instrument by 13 independent evaluators across sites over 4 years. We use multigroup confirmatory factor analysis (MGCFA) to report interrater reliability (IRR) among the evaluators and factor structure for each scale in 206 participants with OCD. The overall IRR for most scales was high (ICC > 0.94) and remained good to excellent throughout the study. Consistent factor structures (configural invariance) were found for all instruments across the sites, while similarity in the factor loadings for the items (metric invariance) could be established only for the DYBOCS and the BABS. It is feasible to achieve measurement fidelity of clinical measures in multisite, multilinguistic global studies, despite the challenges inherent to such endeavors. Future studies should not only report IRR but also consider reporting methods of standardization of data collection and measurement invariance to identify factor structures of core clinical measures. (PsycInfo Database Record (c) 2023 APA, all rights reserved).