Abstract
BACKGROUND: This study assessed the Persian version of the Functioning Assessment Short Test (FAST) in bipolar disorder patients to determine its reliability and validity, as currently no specialized tools are available to evaluate functional impairment in this population. METHODS: A cross-sectional study was conducted with 240 bipolar disorder patients at Shafa Hospital in Rasht in 2023. The Persian version of the FAST was translated and reviewed for content validity, reliability, and factor analysis. Data analysis was done using IBM SPSS version 26, and confirmatory factor analysis (CFA) was performed with LISREL version 8.8. FINDINGS: The results indicated a content validity ratio (CVR) above 0.62. To assess convergent validity, the Short Form Health Survey (SF-36) was used, yielding a direct and significant correlation (P<0.001, r=0.675). The FAST exhibited a Cronbach's alpha of 0.953, indicating robust internal consistency. The intraclass correlation coefficient (ICC) ranged from 0.74 to 0.98, signifying excellent reliability. The correlation coefficient between scores from repeated tests demonstrated strong reliability. CFA was employed to confirm the dimensions of the FAST, and the construct validity was considered satisfactory. CONCLUSION: The Persian version of the FAST demonstrated strong psychometric properties in the study, making it useful for evaluating rehabilitation interventions, assessing medication effects, and supporting research efforts.