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Table 1 Background characteristics of the chronic fatigue syndrome (CFS) group and the healthy control (HC) group in the present study

From: Whole blood gene expression in adolescent chronic fatigue syndrome: an exploratory cross-sectional study suggesting altered B cell differentiation and survival

  CFS group (n = 29) HC group (n = 18) p valuee
Background markers
 Female gender. Number, % 18 62 11 61 0.948
 Scandinavian ethnicity. Number, % 29 100 17 95 0.383
 Age (years). Mean, SD 15.1 1.4 14.7 1.4 0.335
 Body mass index (kg/m2). Mean, SD 20.2 3.4 19.4 1.9 0.317
 Disease duration (months). Median, range 12 4–60 n/a   
 Adheres to the Fukuda criteria of CFSa. Number, % 20 69 n/a   
 Adheres to the Canada 2003-criteria of CFSb. Number, % 11 38 n/a   
Immune markers
 Blood leukocytes (cells × 109/L). Mean, SD 6.0 2.0 5.5 1.0 0.370
 Blood neutrophils (cells × 109/L). Mean, SD 3.1 1.6 2.8 0.7 0.462
 Blood lymphocytes (cells × 109/L). Mean, SD 2.2 0.7 2.1 0.5 0.626
 Blood monocytes (cells × 109/L). Mean, SD 0.48 0.19 0.42 0.10 0.146
 Blood eosinophils (cells × 109/L). Mean, SD 0.18 0.11 0.17 0.07 0.787
 Blood basophils (cells × 109/L). Mean, SD 0.02 0.04 0.02 0.04 0.681
 Serum C-reactive protein (mg/L). Median, IQR 0.40 0.89 0.32 0.28 0.405
 Plasma interleukin-1β (pg/mL). Mean, SD 3.0 2.1 2.3 1.5 0.223
 Plasma interleukin-6 (pg/mL). Mean, SD 10.0 7.5 7.2 4.3 0.158
 Plasma tumor necrosis factor (pg/mL). Mean, SD 63 40 47 29 0.161
Neuroendocrine markers
 Plasma norepinephrine (pmol/L). Mean, SD 2067 835 1530 358 0.004
 Plasma epinephrine (pmol/L). Mean, SD 362 131 284 74 0.012
 Plasma cortisol (nmol/L). Mean, SD 334 151 349 202 0.782
 Urine norepinephrine/creatinine ratio (nmol/mmol). Mean, SD 14.5 6.5 10.9 3.6 0.033
 Urine epinephrine/creatinine ratio (nmol/mmol). Mean, SD 1.7 1.1 1.6 0.9 0.657
 Urine cortisol/creatinine ratio (nmol/mmol). Median, IQR 4.4 3.3 4.5 2.8 0.605
 Heart rate variability, RMSSD (ms). Mean, SDc 83 50 n/a   
 Heart rate variability, LF power (abs). Median, IQRd 541 1068 844 1729 0.445
 Heart rate variability, HF power (abs). Median, IQRd 919 2557 1009 1414 0.666
 Heart rate variability, LF/HF-ratio. Mean, SDd 0.83 0.59 0.90 0.41 0.774
Clinical markers
 Inflammatory symptoms (total score). Mean, SDd 2.1 0.8 1.3 0.5 0.010
 Symptoms of post-exertional malaise (total score). Median, IQRd 4.0 1.5 1.0 0.4 <0.001
 Chalder fatigue questionnaire (total score). Mean, SDd 20.4 5.2 6.8 4.9 <0.001
 Moods and feelings questionnaire (total score). Mean, SDd 20.6 10.8 3.9 3.8 <0.001
 Spielberger state-trait anxiety questionnaire (trait subscore). Mean, SDd 46 9.1 32 3.2 <0.001
 Steps per day (number). Mean, SDd 4698 2622 11,282 4670 0.005
  1. Italics indicate a statistically significant p-value
  2. n/a not applicable, SD standard deviation, IQR interquartile range, RMSSD square root of the mean squared differences of subsequent RR-intervals in the ECG, LF low-frequency power of heart rate variability, HF high-frequency power of heart rate variability
  3. aCf. Ref. [88]
  4. bCf. Ref. [89]
  5. cIn the present study, no data were obtained from the healthy control group
  6. dIn the present study, data were obtained from eight healthy controls only
  7. eBased upon t test, Mann–Whitney test or Fisher exact test as appropriate