Translation and Validation of Tamil Version of Fatigue Severity Scale (FSS) in Individuals with Rheumatoid Arthritis

Fatigue has a significant negative impact on individuals with Rheumatoid Arthritis (RA). Fatigue Severity Scale (FSS) is the most widely used tool to assess fatigue severity which is a common problem in RA. Availability of FSS in local vernacular language could add more value and the study aims to construct the Tamil version of the FSS and validate it among patients with RA. The study was conducted in 2 phases. In phase I, the English version of FSS was translated into Tamil by following the Linguistic Guidelines by mapi eprovide. In Phase II – Validation of Tamil version of FSS was carried out in 50 patients of RA by establishing; Test-retest reliability, Internal consistency, Content validity; and Convergent validity in comparison with HAQ-DI and SF-12 The initial testing between Tamil FSS with English version revealed an intraclass correlation coefficient (ICC) (0.821) and α(0.902). The content validity was established by Cohen’ kappa agreement k which is >80% with a significance <0.004, which shows Good substantial agreement between raters. FSS showed strong positive correlation with HAQ-DI (>0.0005) and negative correlation with SF-12 (>0.0005). The scale demonstrated excellent internal consistency ( α = 0.972) and test-retest reliability (ICC = 0.93). The validated Tamil version demonstrated excellent content validity as well as good internal consistency and test-retest reliability, would be a useful instrument for clinical practice and research. It can be recommended for the assessment of Fatigue severity among Tamil-speaking population with RA.