Table 1.
Baseline characteristics
| Patients with CFS, baseline | Difference/OR | 95% CI of difference/OR | P value | ||
| SEID-negative (n=69) |
SEID-positive (n=45) |
||||
| Gender, n (%) | |||||
| Male | 22 (32) | 10 (22) | 1.64 | 0.69 to 3.90 | 0.262 |
| Female | 47 (68) | 35 (78) | |||
| Age, years, mean (SD) | 15.5 (1.6) | 15.1 (1.6) | −0.35 | −0.95 to 0.26 | 0.264 |
| BMI, kg/m2, mean (SD) | 21.8 (3.9) | 21.2 (4.7) | 0.54 | −2.16 to 1.07 | 0.507 |
| Disease duration, months, median (IQR) | 18 (17) | 15 (16) | 3 | −2 to 11 | 0.101 |
| Symptoms suggesting a mood disorder, total score, mean (SD) | 13.4 (7.6) | 23.2 (10.8) | 9.19 | 5.78 to 12.6 | <0.001 |
| Steps per day, number, mean (SD) | 4824 (2507) | 4342 (2276) | −481 | −1409 to 446 | 0.306 |
| Chalder Fatigue Questionnaire, total score, mean (SD) | 18.1 (5.8) | 20.7 (6.0) | 2.67 | 0.40 to 4.94 | 0.022 |
| School absence, %, median (IQR) | 50.0 (65) | 75.0 (65) | 25.0 | 0.00 to 37.5 | 0.069 |
| Allocation to clonidine vs placebo, n (%) | |||||
| Clonidine | 33 (48) | 25 (56) | 0.73 | 0.34 to 1.56 | 0.420 |
| Placebo | 36 (52) | 20 (44) | |||
P values are based on χ2 test, Student’s t-test or Mann-Whitney’s test, as appropriate. Due to multiple comparisons, the level of significance is considered equal to 0.05/44=0.00114.
BMI, body mass index; CFS, chronic fatigue syndrome; SEID, systemic exertion intolerance disease.