Measuring fatigue in patients with Parkinson's disease - the Fatigue Severity Scale

The objective was to compare the prevalence and severity of fatigue in patients with Parkinson's disease (PD) with that in two control groups, one consisting of randomly chosen control subjects of the same age and sex distribution and the other consisting of patients with coxarthrosis waiting to receive total hip replacement. We also explored the possible correlation of demographic and clinical data to the presence and severity of fatigue. Sixty-six patients with PD, 131 randomly chosen controls and 79 patients with coxarthrosis, waiting to receive total hip replacement, were evaluated for fatigue. Patients and controls with a depressive mood disorder or cognitive impairment had been excluded from the study. Fatigue was measured by the Fatigue Severity Scale (FSS). For the patients with PD the mean total FSS score was 4.1, compared with 2.7 amongst the randomly chosen control group and 2.9 in the group consisting of patients with coxarthrosis. Fifty per cent of the patients with PD had a mean total FSS score of 4 or higher, compared with 25% in both of the two control groups. There was no correlation between pain, presence of self-reported nocturnal sleep disorders or duration of PD and fatigue. The patients with fatigue did have a more advanced disease, measured both by Unified Parkinson's Disease Rating Scale score and Hoehn and Yahr stage. Although the univariate analyses indicated that more severe parkinsonism was correlated to the symptom, the multivariate analysis showed that none of the studied variables were significant explanatory factors for fatigue. Fatigue is a common symptom in patients with PD without depression or dementia. The study indicates that fatigue is an independent symptom of the disease without relation to other motor or non-motor symptoms.