Reliability and validity of the Thai self-report version of the Yale–Brown Obsessive–Compulsive Scale-Second Edition

PURPOSE The self-report version of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) has been developed to overcome the limitations of the clinician-administered version, which needs to be executed by trained personnel and is time consuming. The second edition of the Y-BOCS (Y-BOCS-II) was developed to address some limitations of the original version. However, there is no self-report version of the Y-BOCS-II at the moment. This study aimed to evaluate the psychometric properties of the developed Thai self-report version of the Yale-Brown Obsessive-Compulsive Scale-Second Edition (Y-BOCS-II-SR-T). PATIENTS AND METHODS Y-BOCS-II-SR-T was developed from the Thai version of the Yale-Brown Obsessive-Compulsive Scale-Second Edition (Y-BOCS-II-T). The Y-BOCS-II-SR-T, the Y-BOCS-II-T, the Thai version of the Florida Obsessive-Compulsive Inventory (FOCI-T), the Hamilton Rating Scale for Depression (HAM-D), the nine-item Patient Health Questionnaire (PHQ-9), and the Pictorial Thai Quality of Life (PTQL) instrument were administered to 52 obsessive-compulsive disorder (OCD) patients. Internal consistency for the Y-BOCS-II-SR-T was calculated with Cronbach's alpha coefficient (α), and the factor analyses were completed. Pearson's correlation was used in determining convergent and divergent validity among the other measures. RESULTS The mean score of the Y-BOCS-II-SR-T total score was 20.71±11.16. The internal consistencies of the Y-BOCS-II-SR-T total scores, the obsession subscale, and the compulsion subscale scores were excellent (α=0.94, α=0.90, and α=0.89, respectively). The correlation between each item and the Y-BOCS-II-SR-T total score showed strong correlation for all items. Confirmatory factor analysis with model modification showed adequate fit for obsession and compulsion factor models. The Y-BOCS-II-SR-T had strong correlation with the YBOCS-II-T and the FOCI-T (r s>0.90) and weaker correlation with the HAM-D, PHQ-9, and PTQL (r s<0.60), which implied good convergent and divergent validity. CONCLUSION The Y-BOCS-II-SR-T is a psychometrically sound and valid measure for assessing obsessive-compulsive symptoms.