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Table 2 Final cluster solution-contributing variables

From: Are there subgroups of chronic fatigue syndrome? An exploratory cluster analysis of biological markers

  1: Pain tolerant & good cognitions (n = 40) 2: Restored HPA dynamics (n = 15) 3: Orthostatic intolerance (n = 20) 4: Low-grade inflammation (n = 4) 5: Pain intolerant & poor cognitions (n = 33) 6: High vagal activity (n = 3)
Plasma cortisol, nmol/L-mean (SD) 329 (118) 314 (132) 366 (132) 407 (136) 443 (154) 462 (169)
Urine cortisol:creatinine ratio, nmol/mmol-median (IQR) 3.2 (2.2, 4.4) 14.5 (7.0, 18.4) 3.2 (2.5, 4.9) 3.9 (2.8, 6.2) 3.2 (1.8, 4.4) 3.7 (n.a)
Interferon gamma, pg/mL-median (IQR) 84 (57, 119) 102 (63, 199) 125 (92, 250) 174 (79, 223) 65 (45, 116) 167 (n.a)
IP-10, pg/mL-median (IQR) 345 (261, 479) 419 (225, 467) 314 (323, 410) 2735 (2359, 3803) 313 (174, 502) 557 (n.a.)
HF-HRV supine, ms2-median (IQR) 1264 (422, 3262) 1743 (147, 2630) 869 (526, 2209) 101 (52, 126) 588 (198, 868) 11052 (n.a.)
Δ HR orthostatic response, beats/min-mean (SD) 3.5 (3.2) 2.5 (4.2) 9.9 (4.1) 3.9 (2.6) 4.7 (3.7) 7.8 (6.3)
Δ SI orthostatic response, mL/m2-mean (SD) − 4.3 (2.9) − 3.0 (5.6) − 11.4 (4.1) − 2.8 (5.4) − 4.3 (3.3) − 9.4 (5.0)
Pressure pain threshold, N/cm2-mean (SD) 20.1 (7.6) 16.5 (6.9) 15.2 (5.2) 13.2 (5.7) 9.8 (3.9) 17.1 (7.1)
Digit span forward, total score-mean (SD) 9.3 (2.1) 8.7 (1.5) 8.0 (2.1) 8.5 (2.4) 7.2 (1.2) 8.0 (1.0)
Color-Word interference test condition 2, sec-mean (SD) 25.7 (4.2) 22.9 (4.5) 25.9 (4.4) 25.3 (4.3) 30.2 (9.2) 23.7 (4.2)
  1. HPA: hypothalamus–pituitary–adrenal; CI: confidence interval; IP-10: Interferon gamma-induced protein 10; HR: heart rate; SI: stroke index; HF-HRV: high-frequency power of heart rate variability; IQR: interquartile range (25 and 75 percentile). Δ denotes the response (upright–supine) to orthostatic challenge. The characterizing variable scores within each cluster is highlighted with italics