Table 1 Sample characteristics by Study Group (n = 923)
|  | ME/CFS (n = 595) | HC (n = 328) | p-value |
|---|---|---|---|
Age (yrs), mean (SD) | 47.6 (12.8) | 42.8 (14.7) | < 0.0001 |
Female, n (%) | 433 (72.8) | 216 (65.9) | 0.0276 |
Racea, n (%) |  |  | < 0.0001 |
 White | 525 (88.2) | 187 (57.0) |  |
 Black/African American | 12 (2.0) | 22 (6.7) |  |
 All others | 28 (4.7) | 85 (25.9) |  |
Ethnicitya, n (%) |  |  | < 0.0001 |
 Hispanic | 39 (6.6) | 94 (28.7) |  |
 Non-Hispanic | 472 (79.3) | 187 (57.0) |  |
Marital Statusa, n (%) | Â | Â | 0.9047 |
 Married/committed | 308 (51.8) | 164 (50.0) |  |
 Previously married | 103 (17.3) | 56 (17.1) |  |
 Never married | 171 (28.7) | 99 (30.2) |  |
Employmenta, n (%) |  |  | < 0.0001 |
 Full-time | 89 (15.0) | 177 (54.0) |  |
 Part-time | 65 (10.9) | 58 (17.7) |  |
 Not working | 415 (69.7) | 83 (25.3) |  |
Had insurance, n (%) | 549 (92.3) | 266 (81.1) | < 0.0001 |
Educationa, n (%) | Â | Â | 0.1299 |
 Less than high school | 4 (0.7) | 5 (1.5) |  |
 High school graduate | 131 (22.0) | 94 (28.7) |  |
 College graduate | 234 (39.3) | 119 (36.3) |  |
 Post college | 208 (35.0) | 102 (31.1) |  |
Number of office visit, mean (SD) | 4.7 (12.86) | 0.6 (1.24) | < 0.0001 |
BMI, mean (SD) | 26.6 (6.12) | 26.1 (5.48) | 0.2602 |
Obesity, n (%) | 111 (18.7) | 55 (16.8) | 0.2226 |
Illness Duration (yrs), mean (SD) | 13.6 (10.25) | Â | Â |
Illness Onseta, n (%) | Â | Â | Â |
 Gradual | 205 (34.5) |  |  |
 Sudden | 352 (59.2) |  |  |
COPC Index Score (0–6), mean (SD) | 1.8 (1.45) | 0.2 (0.43) | < 0.0001 |
Number of COPCs, n (%) |  |  | < 0.0001 |
 0 | 142 (23.9) | 271 (82.6) |  |
 1 | 151 (25.4) | 52 (15.9) |  |
 2 | 123 (20.7) | 5 (1.5) |  |
 3 or more | 179 (30.0) | 0 (0) |  |