Impact of fatigue in Parkinson's disease: the Fatigue Impact Scale for Daily Use (D-FIS).

The Fatigue Impact Scale for Daily Use (D-FIS) was used in a cross-sectional study including 142 consecutive Parkinson's disease (PD) patients. Usual clinical measures for PD, the Montgomery-Asberg Depression Rating Scale and the Parkinson's Disease Questionnaire-8 items were applied. In addition to the D-FIS, patients with fatigue (67.6%, PWF) completed the Multidimensional Fatigue Inventory (MFI), a visual analogue scale for fatigue (VAS-F) and a Global Perception of Fatigue scale (GPF). Relevant psychometric D-FIS results were: floor effect = 4.2%; ceiling effect = 1.1%; skewness = 0.44; item homogeneity = 0.63; Cronbach's alpha = 0.93; item-total correlation = 0.68 (item 1)-0.82 (item 8); standard error of measurement = 2.15; convergent validity with other fatigue measures = 0.54 [GPF]-0.62 [VAS-F] (p<0.001). In a multiple linear regression model, fatigue, depression, and disability independently influenced HRQoL, as measured by the PDQ-8. Patients on amantadine had lower prevalence of fatigue. In PD, D-FIS is a consistent and valid measure for fatigue, a frequent symptom previously found to impair patients' HRQoL. Fatigue was also linked to depression and disability in this study.