Table 1.
Description of healthy controls (HC) and patients with chronic fatigue syndrome and fibromyalgia (CFS/FM) including clinical data, measures from conditioned pain modulation, cytokine expression, DNA methylation, and prevalence of polymorphisms. Data is reported as the mean estimate and standard error (SE) of both assessments (at Day 1 and Day 4) from the repeated measure mixed linear models and include subjects as random factor, time as repeated effect, group and haplotype as fixed effects, and age, body-mass index and symptoms at the CSL questionnaire as covariates, as described in the statistical analyses. CSL: chronic fatigue syndrome symptom list. CPM: conditioned pain modulation (# numbers should be interpreted as the higher the number the better the descending modulation); IL-6: interleukin-6; IFN-γ: interferon-γ; TGF-β: transformative growth factor-β; COMT: Catechol-O-methyltransferase. C.I.: confidence interval. *between-group significant differences at p < .05. χ: Chi-squared Test’s value
| HC n = 26 |
CFS/FM n = 28 |
Mean difference (95% C.I.) |
p | |
|---|---|---|---|---|
| Clinical | ||||
| CSL Total | 23.51 (5.04) | 99.80 (5.69) | 76.29 (61.88; 90.69) | < 0.001* |
| CPM (°C) # | ||||
| To cold stimuli | 1.89 (0.37) | 2.16 (0.43) | 0.271 (-0.787; 1.33) | 0.610 |
| To heat stimuli | 0.92 (0.28) | 0.98 (0.31) | 0.059 (-0.71; 0.82) | 0.878 |
| Cytokines | ||||
| IL-6 (pg/mL) | 0.71 (0.26) | 1.30 (0.22) | 0.591 (-0.135; 1.32) | 0.109 |
| IFN-γ (pg/mL) | 12.29 (1.22) | 6.62 (1.50) | -5.66 (-9.70; -1.62) | 0.007* |
| TGF-β (ng/mL) | 12.18 (1.03) | 13.07 (1.12) | 0.89 (-2.44; 4.22) | 0.597 |
| DNA Methylation (%) | ||||
| MB-COMTa | 2.39 (0.183) | 2.78 (0.21) | 0.39 (-0.14; 0.94) | 0.465 |
| MB-COMTb | 1.55 (0.12) | 1.54 (0.13) | 0.07 (-0.53; 0.52) | 0.978 |
| MB-COMTc | 1.70 (0.29) | 3.12 (0.31) | 1.42 (0.52; 2.32) | 0.003* |
| Mean MB-COMT | 1.94 (0.22) | 2.74 (0.23) | 0.80 (0.14; 1.45) | 0.018* |
| S-COMTa | 61.63 (1.22) | 62.47 (1.37) | 0.81 (-3.23; 4.85) | 0.691 |
| S-COMTb | 93.39 (0.36) | 93.90 (0.39) | 0.50 (-0.53; 1.53) | 0.334 |
| S-COMTc | 91.74 (0.34) | 92.18 (0.38) | 0.44 (-0.68; 1.56.71) | 0.436 |
| Mean S-COMT | 81.13 (0.50) | 81.71 (0.56) | 0.58 (-1.07; 2.23) | 0.487 |
| Polymorphism (n) | ||||
| rs4633 (TT/CT/CC) | 4/15/7 | 4/21/3 | 2.529χ | 0.287 |
| rs4818 (CC/GC/GG) | 5/15/6 | 7/16/5 | .072χ | 0.965 |
| rs4680 (AA/GA/GG) | 4/15/7 | 5/20/3 | 2.930χ | 0.403 |