Psychometric Features of the Persian Version of the Fatigue Impact Scale in Iranian Stroke Patients

Background and Objective: Post-stroke fatigue is a troublesome symptom and a common complaint of stroke patients. The purpose of this study was to investigate the psychometric features of the Persian version of the FIS (FIS-P) administered to Iranian stroke patients. Materials and Methods: In this cross-sectional methodological study, the psychometric properties of the Persian version of the FIS (FIS-P) were examined. The participants were 280 Iranian people (140 healthy adults; 140 stroke patients) who were assessed using the FIS-P, fatigue severity scale (FSS), and SF-36 questionnaire. The content, convergent, and discriminant validity of the FIS-P were evaluated using CVR and CVI, Pearson correlation, and independent-sampling T-tests, respectively. Furthermore, inter-rater reliability and test-retest reliability were assessed via the intra-class correlation coefficient and SEM. The internal consistency reliability was evaluated using Cronbach’s α. Results: The results of the CVR for items ranged from 0.6-1, and the CVI of the FIS-P was 0.85. The Pearson correlation measure revealed strong and inverse correlations between FIS-P and FSS and a low to moderate relationship between all subscales of the SF-36 and FIS-P in terms of convergent validity. T-test results showed the discriminant validity of the FIS-P in differentiating between stroke patients and healthy participants. The ICC coefficients for test-retest and inter-rater reliability for the overall scale were 0.991 and 0.984, respectively. Cronbach’s α was 895. Conclusion: The strong psychometric properties of the FIS-P indicated its applicability in assessing the impact of fatigue on stroke victim’s daily activities and the effectiveness of therapeutic and rehabilitation interventions.