Augusta University, USA
Title: The dimensionality of fatigue in parkinson's disease
Biography: Raymond Chong
Fatigue is commonly reported among individuals with Parkinson’s disease (PD). It may occur before the overt symptoms of bradykinesia, rigidity and tremor. As very little is understood about how to measure it, we determined the dimensionality of fatigue in PD using four recommended scales, the Fatigue Severity Scale (FSS), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), Parkinson Fatigue Scale (PFS) and Visual Analog Fatigue Scale (VAFS). Quality of life measures including cognition, depression, sleep, life orientation, physical activity and PD symptoms were tested for their correlations with fatigue. The results showed that fatigue was associated with many quality of life variables, with the PDQ-39 summary index showing the strongest association. PD subjects agreed more strongly than caregivers that they experienced higher levels of fatigue. 27% of PD subjects rated fatigue as one of their top three most bothersome symptoms. The constructs of fatigue were captured within one dimension by the VAFS which explained 67% of the total variance. The highest likelihood ratio gave a cut-off score of < 5.5 on the VAFS. The change in scores required to produce a perceptible difference or is grossly observable ranged between 1.4 and 2.2 points respectively. The potential utility of a single measure such as the VAFS in PD that is reliably correlated with quality of life is consistent with the pursuit to develop clinical tests and measurements that are accessible, easy to use and universally interpretable across health science disciplines. It is hoped that the simplified method of quantifying fatigue may be useful in studying movement disorders in PD.