Table 1.
Participants’ characteristics by illness groups
| Characteristicsa | All (n = 639) |
CFS-X (n = 77, 12%) |
CFS (n = 64, 10%) |
ISF (n = 302, 47%) |
NF (n = 196, 31%) |
p-value |
|---|---|---|---|---|---|---|
| Age, mean (SEM) | 48.07 (0.38) | 49.99 (1.11) | 47.75 (1.21) | 48.06 (0.58) | 47.44 (0.68) | 0.2725 |
| BMI, mean (SEM) | 28.13 (0.21) | 28.29 (0.56) | 28.86 (0.68) | 28.82 (0.32) | 26.77 (0.36) | 0.0003 |
| WHR (SEM) | 0.85 (0.00) | 0.85 (0.01) | 0.85 (0.01) | 0.86 (0.004) | 0.83 (0.01) | 0.0025 |
| Sex | 0.0009 | |||||
| Female | 477 (74.64%) | 64 (83.12%) | 58 (90.63%) | 222 (73.51%) | 133 (67.87%) | |
| Race | 0.0127 | |||||
| White | 488 (76.37%) | 60 (77.92%) | 51 (79.69%) | 219 (72.51%) | 158 (80.61%) | |
| Black | 139 (21.75%) | 13 (16.88%) | 10 (15.63%) | 79 (26.16%) | 37 (18.88%) | |
| Other | 12 (1.87%) | 4 (5.19%) | 3 (4.69%) | 4 (1.32%) | 1 (0.51%) | |
| Residential area | 0.1621 | |||||
| Urban | 216 (33.80%) | 26 (33.77%) | 22 (34.38%) | 109 (36.09%) | 59 (30.10%) | |
| Metro | 106 (16.58%) | 7 (9.09%) | 7 (10.94%) | 49 (16.23%) | 43 (21.94%) | |
| Rural | 317 (49.61%) | 44 (57.14%) | 35 (54.69%) | 144 (47.68%) | 94 (47.96%) | |
| Education | < 0.0001 | |||||
| Less than High School | 34 (5.33%) | 13 (16.88%) | 2 (3.13%) | 14 (4.65%) | 5 (2.56%) | |
| ≥ HS ≤ 2 year College | 349 (54.78%) | 51 (66.23%) | 40 (62.50%) | 177 (58.80%) | 81 (41.54%) | |
| 4-year College | 110 (17.27%) | 5 (6.49%) | 7 (10.94%) | 47 (15.61%) | 51 (26.15%) | |
| Graduate | 144 (22.60%) | 8 (10.39%) | 15 (23.44%) | 63 (20.93%) | 58 (29.74%) | |
| Income | < 0.0001 | |||||
| ≤ $20,000 | 78 (12.74%) | 22 (31.88%) | 9 (14.75%) | 41 (14.04%) | 6 (3.16%) | |
| $20,001–$40,000 | 102 (16.67%) | 9 (13.04%) | 12 (19.67%) | 59 (20.21%) | 22 (11.58%) | |
| ≥ $40,001 | 432 (70.59%) | 38 (55.07%) | 40 (65.57%) | 192 (65.75%) | 162 (85.26%) | |
| Illness duration in year, mean (SEM)b | 10.99 (0.95) | 9.83 (1.10) | 12.40 (1.61) | Not applicable | Not applicable | 0.1796 |
| Post-exertional malaise | ||||||
| Yes | 191 (29.89%) | 65 (84.42%) | 52 (81.25%) | 70 (23.18%) | 4 (2.04%) | < 0.0001 |
aValues for age, BMI, WHR and illness duration are mean (SEM). Values for all other characteristics are number of participants with percentages in parenthesis
bNumber of subjects with information on illness duration were 86, 47 and 39 corresponding to columns All, CFS-X and CFS