Demographic and Clinical Characteristics
Overall, 462 of 678 (68%) consecutively evaluated clinic patients completed the questionnaire. Of these 462, 44 patients had a friend who completed the 4 activity items; these 44 patients and their friends constituted the study sample. The 44 patients tended to be older than the larger clinic population (43.6 vs. 39.6 years, p = 0.02), but did not differ in gender (84% vs. 74% female), marital status (50% vs. 50% married), duration of fatigue (5.9 vs. 5.2 years), or proportion diagnosed with CFS (57% vs. 56%) or fibromyalgia (21% vs. 23%). Likewise, our study sample had rates similar to those of all clinic patients for lifetime diagnoses of alcohol abuse (14% vs. 16%), major depression (69% vs. 65%), dysthymic disorder (26% vs. 22%), generalized anxiety disorder (17% vs. 24%), panic disorder (26% vs. 19%), and somatization disorder (29% vs. 21%). However, they tended to be diagnosed more often with melancholic depression (11% vs. 5%, p = 0.02).
Of the 44 fatigued clinic patients, we limited our analysis to the 33 who met criteria for CFS, idiopathic chronic fatigue, and/or fibromyalgia. The other 11 patients were excluded for medical or psychiatric conditions that could explain their fatigue [
21]. The demographic and clinical characteristics of the 33 patients and their 33 matched controls are presented in Table
1. Patients and controls did not differ in age (
p = 0.22) or sex (
p = 0.50). Of the 33 patients with chronic, unexplained, debilitating fatigue, 25 (76%) met the criteria for CFS, 7 (21%) met the criteria for idiopathic chronic fatigue, and 9 (27%) met criteria for fibromyalgia. Only 1 had fibromyalgia alone, without CFS or idiopathic chronic fatigue.
Table 1
Demographic and clinical characteristics of patients and healthy control subjects
Demographic
| | |
Number | 33 | 33 |
Age, mean years (SD)
| 45.6 (11.8) | 44.1 (13.1) |
Female, n (%)
| 26 (79) | 28 (85) |
Clinical
| | |
CFS criteria met, n (%)
| 25 (76) | --- |
Idiopathic chronic fatigue criteria met n (%)
| 7 (21) | |
Fibromyalgia criteria met 1, n (%)
| 9 (27) | --- |
Table
2 illustrates that, compared with their matched controls, the 33 patients rated themselves as more active before the onset of illness (Z score -3.05,
p = 0.002) and less active currently (Z score -4.72,
p < 0.001). More specifically, in the previous 24 hours, patients reported standing or walking 5 hours less than their healthy friends (Z score -4.39,
p < 0.001) and lying or reclining 4 hours more (Z score -4.29,
p < 0.001), with no differences in the time spent sitting (Z score -0.86,
p = 0.39). For both patients and controls, the activity reported during the previous 24 hours represented a typical day (Z score -1.12,
p = 0.26).
Table 2
Previous and current activity levels of patients and healthy control subjects
Previous activity level
1,2, median (IQR) 3
| 9 (8 – 9.5) | 8 (6.5 – 8.5)* |
Previous activity level,
n (%)
| | |
Level 1 | 0 | 0 |
Level 2 | 0 | 0 |
Level 3 | 0 | 1 (3) |
Level 4 | 1 (3) | 1 (3) |
Level 5 | 0 | 2 (6) |
Level 6 | 1 (3) | 4 (12) |
Level 7 | 3 (9) | 5 (15) |
Level 8 | 8 (24) | 12 (36) |
Level 9 | 12 (36) | 5 (15) |
Level 10 | 8 (24) | 3 (9) |
Last week's activity
2, median (IQR) 3
| 3 (2 – 5) | 8 (6 – 8) †
|
Last week's activity, n (%)
| | |
Level 1 | 5 (15) | 0 |
Level 2 | 6 (18) | 0 |
Level 3 | 7 (21) | 1 (3) |
Level 4 | 4 (12) | 2 (6) |
Level 5 | 5 (15) | 3 (9) |
Level 6 | 3 (9) | 4 (12) |
Level 7 | 1 (3) | 5 (15) |
Level 8 | 2 (6) | 11 (33) |
Level 9 | 0 | 4 (12) |
Level 10 | 0 | 3 (9) |
Last 24 hours' activities,
median hours (IQR)
3
| | |
Standing or walking | 4 (2 – 5) | 9 (7.5 – 12) †
|
Sitting | 6 (5 – 9) | 6 (4 – 8) |
Reclining or lying down | 12 (10 – 16) | 8 (8 – 9.5) †
|
Activity Level in Last 24 Hours, %
4
| | |
Higher than recently | 6 | 24 |
Lower than recently | 45 | 27 |
Average | 49 | 48 |
Lastly, we considered premorbid and current activity levels in the CFS and fibromyalgia subgroups. These results are not displayed in the table. The median rating (and interquartile range) for premorbid activity level was 9 (8 – 9.5) among the 25 CFS patients versus 8 (7 – 9) among controls (Z = -2.18, p = 0.03). Among CFS patients, the median rating (and interquartile range) for current activity was 3 (2 – 5) versus 8 (6.5 – 8.5) among controls (Z = -4.23, p ≤ 0.001). In the 9 patients with fibromyalgia, the median rating (and interquartile range) for premorbid activity was 9 (8 – 9.5) versus 8 (7 – 8.5) among controls (Z = -2.46, p = 0.01), and the current activity was lower: 4 (1.5 – 4.5) versus 7 (6 – 8) (Z = -2.53, p = 0.01).