Validity and reliability of the fatigue impact scale in stroke

Abstract

Background Fatigue is one of the significant problems of post-stroke patients as it causes a decreased quality of life. Although the fatigue impact scale (FIS) is used in stroke, it lacks validation studies. Objective This study evaluates the psychometric properties of the FIS in patients with stroke. Subjects and Methods A total of 41 subjects with stroke and 41 control subjects admitted to Physical Medicine and Rehabilitation Department were included. Convergent validity was assessed using the SF-36 vitality (SF-36 v) scale and the fatigue severity scale (FSS). Divergent validity was assessed using the Hospital Anxiety and Depression Scale (HADS). Results All subscores of the FIS were significantly higher in the stroke group than in the control group (p < .05). FIS showed excellent internal consistency in stroke patients (Cronbach's alpha = 0.946). There was a negative correlation among FIS and SF-36 v (r = -0.506, p = .001), and a positive correlation between the HADS anxiety score (r = 0.356, p = .026) and the HADS depression score (r = 0.293, p = .071). FIS total scores were weakly correlated with the FSS (r = 0.323, p = 0.039). The test-retest reliability of FIS was good in terms of its cognitive, physical, and psychosocial subscales and total scores, with ICC values of 0.78, 0.73, 0.80, and 0.83, respectively. Conclusion FIS is a valid and reliable multidimensional scale that sensitively discriminated fatigue in the stroke patients from that in the control subjects.