Demographic Influences on the Relationship Between Fatigue and Quality of Life in Parkinson's Disease

Background: Fatigue has a major impact on health-related quality of life (HR-QOL) in Parkinson's disease (PD). Objectives: To determine whether demographic characteristics modify the relationship between fatigue and HR-QOL. Methods: Patients with PD in the Fox Insight study completed the Parkinson Fatigue Scale (PFS-16) and Geriatric Depression Scale (GDS-15). Linear regression examined the relationship between the PFS-16 and Parkinson Disease Quality of Life, as modified by age, sex, and GDS-15. Results: A total of 1029 participants (44% female, mean age 67.4 years, and mean disease duration 4.6 years) were included in this analysis. Multivariable regression modeling demonstrated a negative effect modification for age (beta = -0.07, P < 0.001) and a positive effect modification for the GDS-15 (beta = 0.057, P = 0.002), but not for sex (beta = -0.021, P = 0.231). Conclusion: The association between fatigue and worse HR-QOL is greater at younger ages and in individuals with more depressive symptoms. Targeted therapeutics for these individuals may provide the greatest impact on fatigue in PD.