Table 3.
PCAs of background data, psychometric, and cytokines in fibromyalgia and healthy controls taken together.
| Variables | p[1] | p[2] | p[3] | p[4] |
|---|---|---|---|---|
| Age | 0.06 | −0.14 | 0.34 | −0.15 |
| Weight | 0.12 | −0.06 | 0.17 | 0.41 |
| Height | −0.02 | −0.19 | −0.06 | 0.19 |
| BMI | 0.15 | −0.07 | 0.20 | 0.36 |
| Systolic BP | 0.07 | −0.19 | 0.34 | 0.13 |
| Diastolic BP | 0.08 | −0.13 | 0.34 | 0.16 |
| VAS global pain intensity | 0.29 | −0.03 | −0.13 | 0.03 |
| PPT | −0.23 | −0.04 | 0.07 | −0.04 |
| Hand grip force | −0.25 | −0.03 | −0.12 | 0.33 |
| Elbow flexion force | −0.26 | −0.04 | −0.13 | 0.32 |
| Knee extension force | −0.21 | −0.02 | −0.13 | 0.40 |
| 6MWT | −0.26 | 0.12 | −0.15 | 0.02 |
| PDI | 0.20 | −0.07 | −0.20 | 0.02 |
| HADS depression | −0.22 | −0.11 | 0.23 | −0.11 |
| HADS anxiety | 0.25 | −0.07 | −0.22 | 0.10 |
| PCS | 0.30 | −0.08 | −0.13 | 0.09 |
| SF36-PCS | 0.30 | −0.07 | −0.13 | 0.06 |
| SF36-MCS | −0.29 | 0.07 | 0.05 | −0.06 |
| FIQ | −0.24 | −0.11 | −0.15 | 0.27 |
| IFN-γ | 0.08 | 0.34 | 0.11 | 0.06 |
| IL-1β | 0.21 | −0.08 | −0.23 | 0.09 |
| IL-2 | −0.04 | 0.20 | −0.01 | 0.03 |
| IL-6 | 0.06 | 0.39 | 0.00 | 0.13 |
| IL-8 | 0.00 | 0.07 | 0.03 | 0.11 |
| IL-10 | 0.09 | 0.27 | 0.06 | 0.07 |
| IL-17A | 0.10 | 0.35 | −0.02 | 0.13 |
| TNF-α | 0.07 | 0.40 | 0.02 | 0.10 |
| IL-1ra | 0.08 | 0.36 | 0.08 | 0.05 |
| IP-10 | 0.03 | −0.03 | 0.11 | 0.06 |
| MCP-1 | 0.04 | 0.07 | 0.21 | 0.18 |
| eotaxin | 0.01 | −0.08 | 0.30 | 0.08 |
|
| ||||
| R 2 | 0.26 | 0.11 | 0.09 | 0.07 |
| Q 2 | 0.23 | 0.08 | 0.03 | 0.04 |
PCA = principle component analysis. Four significant components (p[1]-p [4]) were obtained. For each component are reported the loadings of the included variables. High absolute loadings (>0.20) are most important for the component. Variables with high absolute loadings are intercorrelated; the same sign indicate a positive intercorrelation while different signs for two variables with high loadings indicate a negative correlation. R 2 and Q 2 are reported for each component at the two bottom rows. R 2 (cumulative) = 0.53, Q 2 (cumulative) = 0.34. The loadings of the most important variables for the four components are denoted with bold type. BMI = body mass index; BP = blood pressure9; FIQ = fibromyalgia impact questionnaire; HADS = hospital anxiety and depression scale; PDI = pain disability index; PPT = pressure pain thresholds (mean of 8 sites); SF36 = Short Form Health Survey 36, physical (PSC) and mental summary components (MSC); 6MWT = 6-min walk test; VAS = visual analogue scale.