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.