Table 1

 Characteristics of adolescents with and without CFS and their respective parents

CFS casesHealthy controlsMean difference
(n = 32)(n = 167)(95% CI)
Values are mean (SD) unless otherwise indicated. 95% CI, 95% confidence interval corresponding with a p value <0.05.
Age (years)16.0 (1.7)15.5 (1.6)0.5 (−0.1 to 1.2)
Gender (% girls)886028 (9 to 45)
Median illness duration in months (range)27 (6–192)NA
Mean total hours physical exercise per week (h/wk)2.3 (3.3)8.0 (3.9)−5.7 (−7.2 to −4.2)
School type level 1 (%)19200 (−15 to 16)
School type level 2 (%)81800 (−15 to 16)
Minimal school absence (less than 5% last 6 months) (n (%))4 (13)149 (89)−76 (−89 to −65)
Considerable school absence (5–50%) (n (%))19 (59)18 (11)48 (35 to 62)
Almost complete school absence (50–100%) (n (%))9 (28)028 (21 to 35)
Fatigue assessment: Checklist Individual Strength
(20 items, 7-point Likert scale)45.2 (11.0)22.9 (11.0)22.2 (18.0 to 26.4)
    Total score subscale subjective fatigue (8 items)21.6 (8.7)15.2 (7.0)6.3 (3.0 to 9.6)
    Total score subscale concentration (5 items)13.5 (5.2)9.0 (4.0)4.5 (2.5 to 6.4)
    Total score subscale motivation (4 items)14.4 (4.9)7.4 (3.8)7.1 (5.3 to 8.9)
    Total score subscale physical activity (3 items)
Self-reported sporting activities
    Mothers, % active on outdoor sports4776−29 (−46 to −12)
    Fathers, % active on outdoor sports4762−15 (−34 to 4)
Prevalence (%) of self-reported fatigue in parents
    Fatigue in mothers562135 (6 to 64)
    Fatigue in fathers1317−4 (−19 to 11)