The Parkinson fatigue scale: an evaluation of its validity and reliability in Greek Parkinson's disease patients.

Objective: Fatigue is one of the most frequent and important nonmotor symptoms of patients with Parkinson disease (PD), affecting quality of life. Although, in some cases, it may be a severe and debilitating complaint, it remains relatively unexplored. The PFS-16 is a fatigue measure, specifically designed for PD patients. The aim of this study was to investigate the psychometric properties of Parkinson fatigue scale (PFS-16) in Greek PD patients.

Methods: In total, 99 patients with PD were assessed. The following psychometric properties were tested: data quality, floor/ceiling effects, reliability (internal consistency, test-retest reliability), and construct validity. Construct validity was evaluated by examining correlations with other variables including other fatigue measures such as Fatigue Severity Scale (FSS) and the vitality scale (SF-VT) of SF-36. Moreover, assumptions were explored about "known" groups concerning fatigue.

Results: The mean score for the PFS-16 was 2.95 (± 0.91); acceptability was good with negligible floor and ceiling effects. Results showed high internal consistency (Cronbach's alpha, 0.96) and test-retest reliability (ICC, 0.93). Strong correlations were observed between the PFS-16 and other fatigue (FFS and SF-VT) measures (rs = 0.77 and - 0.70, p < 0.001), revealing appropriate validity. Furthermore, predictions for "known" groups validity were verified.

Conclusion: The Greek version of the PFS-16 showed satisfactory reliability and validity and thus can be regarded as a useful tool in assessing fatigue in PD.