Table 6.

OPLS of global pain intensity previous seven days in FM. Regressors used data from spectroscopy and microdialysis (except pain variables from microdialysis) (cf. Table 3 and Table 4). The regression had one predictive component. Only significant variables are shown (i.e., variables with VIP > 1.0 and absolute p(corr) ≥ 0.50).

Variables	VIP	p(corr)
Pi/PCr	1.71	0.65
Mean Blood flow Trapezius 140–220 min	1.70	−0.64
Glutamate Trapezius 160 min	1.53	−0.57
Blood flow Trapezius 140 min	1.52	−0.57
Blood flow Erector spinae 140 min	1.51	−0.57
Pi/Ptot	1.51	0.57
PCr/Ptot	1.51	−0.57
Difference Pyruvate Erector spinae 160 min–140 min	1.48	0.56
Pyruvate Erector spinae 160 min	1.48	0.56
Blood flow Trapezius 160 min	1.48	−0.55
Difference Glutamate Erector spinae 160 min–140 min	1.46	0.55
Mean Pyruvate Erector spinae 140–220 min	1.46	0.55
Difference Glucose Erector spinae 160 min–140 min	1.39	0.52
PCr	1.38	−0.53
Mean Blood flow Erector spinae 140–220 min	1.37	−0.51
Blood flow Erector spinae 160 min	1.35	−0.51
R2	0.52
Q2	0.32
CV-ANOVA p-value	0.006
n	30

VIP and p(corr) are reported for each regressor (i.e., the loading of each variable scaled as a correlation coefficient and therefore standardizing the range from −1 to + 1). The sign of p(corr) indicates the direction of the correlation with the dependent variable (+ = positive correlation; − = negative correlation). Hence, a positive p(corr) for a certain variable indicates a positive correlation with pain intensity in FM in the multivariate context. The four bottom rows report R², Q², P-value of the CV-ANOVA, and number of subjects included in the regression (n) from the second OPLS regression (see Statistics for details).