Table 3.

Principal component analysis; rotated component matrix

	C 1	C 2	C 3	C4
PDQ	0.224	0.213	0.951	0.006
NP	0.949	0.139	0.201	− 0.211
TBP	0.928	0.185	0.201	0.255
PP	0.176	0.963	0.205	0.006

Method of extraction: principal component analysis

Method of rotation: Caesar normal maximum variance method

Rotation converged in 5 iterations

P < 0.01 by Bartlett’s test; the results of first principal component calculation were as follows: F1 = 0.881 × (nocturnal pain) + 0.899 × (total back pain) + 0.703 × (neuropathic pain) + 0.639 × (peripheral pain)

The weight of neuropathic pain was greater than peripheral pain in the first principal component (0.703 vs. 0.639). Common factors (CF) of pain calculated by rotated component matrix analysis: CF 1 represents nocturnal pain and low back pain; CF 2 represents peripheral pain; and CF 3 represents PDQ

C component, PDQ pain detection questionnaire, NP nocturnal pain, TBP total back pain, PP peripheral pain