Purpose: Fatigue is one of the most frequent complaints of patients with multiple sclerosis (MS). The Fatigue Impact Scale (FIS), one of the 30 available fatigue questionnaires, is commonly applied because it evaluates multidimensional aspects of fatigue. The main purposes of this study were to test the validity, test-retest reliability, and internal consistency of the Hungarian version of the FIS.
Methods: One hundred and eleven MS patients and 85 healthy control (HC) subjects completed the FIS and the Beck Depression Inventory, a large majority of them on two occasions, 3 months apart.
Results: The total FIS score and subscale scores differed statistically between the MS patients and the HC subjects in both FIS sessions. In the test-retest reliability assessment, statistically, the intraclass correlation coefficients were high in both the MS and HC groups. Cronbach's alpha values were also notably high.
Conclusions: The results of this study indicate that the FIS can be regarded as a valid and reliable scale with which to improve our understanding of the impact of fatigue on the health-related quality of life in MS patients without severe disability.