Table 4.
Simple statistics and standardized Cronbach coefficient alpha of the fatigue scales
| Item | Label | Mean (SD) | Range | Standardized Cronbach coefficient alpha |
|---|---|---|---|---|
| Fatigue Severity Scale (FSS) | ||||
| 1 | My motivation is lower when I am fatigued | 4.3 (1.9) | 1–7 | 0.969 |
| 2 | Exercise brings on my fatigue | 3.2 (1.7) | 1–7 | 0.970 |
| 3 | I am easily fatigued | 3.8 (2.3) | 1–7 | 0.967 |
| 4 | Fatigue interferes with my physical functioning | 3.4 (2.0) | 1–7 | 0.968 |
| 5 | Fatigue causes frequent problems for me | 3.1 (2.2) | 1–7 | 0.967 |
| 6 | My fatigue prevents sustained physical functioning | 3.3 (2.2) | 1–7 | 0.967 |
| 7 | Fatigue interferes with carrying out certain duties and responsibilities | 3.4 (2.1) | 1–7 | 0.967 |
| 8 | Fatigue is among my most disabling symptoms | 3.4 (2.4) | 1–7 | 0.967 |
| 9 | Fatigue interferes with my work, family, or social life | 3.6 (2.3) | 1–7 | 0.967 |
| Parkinson Fatigue Scale (PFS) | ||||
| 1 | I have to rest during the day | 3.0 (1.4) | 1–5 | 0.968 |
| 2 | My life is restricted by fatigue | 2.5 (1.4) | 1–5 | 0.967 |
| 3 | I get tired more quickly than other people I know | 2.9 (1.5) | 1–5 | 0.967 |
| 4 | Fatigue is one of my three worst symptoms | 2.8 (1.6) | 1–5 | 0.967 |
| 5 | I feel completely exhausted | 2.3 (1.4) | 1–5 | 0.967 |
| 6 | Fatigue makes me reluctant to socialise | 2.2 (1.4) | 1–5 | 0.968 |
| 7 | Because of fatigue it takes me longer to get things done | 3.0 (1.5) | 1–5 | 0.967 |
| 8 | I have a feeling of ‘heaviness’ | 2.2 (1.3) | 1–5 | 0.968 |
| 9 | If I wasn’t so tired I could do more things | 2.8 (1.4) | 1–5 | 0.967 |
| 10 | Everything I do is an effort | 2.3 (1.3) | 1–5 | 0.967 |
| 11 | I lack energy for much of the time | 2.6 (1.3) | 1–5 | 0.967 |
| 12 | I feel totally drained | 2.4 (1.3) | 1–5 | 0.967 |
| 13 | Fatigue makes it difficult for me to cope with everyday activities | 2.4 (1.3) | 1–5 | 0.967 |
| 14 | feel tired even when I haven’t done anything | 2.4 (1.3) | 1–5 | 0.968 |
| 15 | Because of fatigue I do less in my day than I would like | 2.7 (1.4) | 1–5 | 0.967 |
| 16 | I get so tired I want to lie down wherever I am | 2.1 (1.4) | 1–5 | 0.967 |
| Visual Analog Fatigue Scale (VAFS) | ||||
| – | Visual Analog Fatigue Scale | 6.5 (2.7) | 2–10 | 0.979 |
The one-factor solution comprising all the items of the three scales explained 67% of the total variance, suggesting that the items from the three scales were unidimensional. The overall standardized alpha coefficient was 0.97. The most reliable item was the VAFS, with a coefficient of 0.979