An increased response to experimental muscle pain is related to psychological status in women with chronic non-traumatic neck-shoulder pain

Table 4 Outcome of the multivariate correlation analysis (principal component analysis; PCA) in the trapezius myalgia group (NSP; n = 19)

		PC1	PC2	PC3	PC4
Clinical neck-shoulder pain
	Current pain area size	0.20	-0.22	0.21	0.16
	Worst pain area size	0.08	-0.27	0.17	0.29
	Least pain area size	0.02	0.01	0.32	0.02
	Pain duration	0.18	0.21	0.02	0.08
	Neck pain intensity	-0.13	0.30	-0.17	0.00
	Shoulder pain intensity	0.04	0.30	-0.19	-0.12
Pain after hypertonic saline infusion
	Area under VAS curve	0.18	0.13	0.05	0.30
	Mean VAS	0.19	0.14	0.10	0.37
	Pain onset	-0.09	-0.10	-0.40	0.09
	Peak VAS	0.14	0.22	0.12	0.36
	Time to peak	0.00	-0.26	-0.15	0.04
	Total pain area size	0.13	-0.18	0.04	0.27
	Referred pain area size	0.07	-0.28	0.01	0.20
Pressure pain thresholds
	Mean PPT Trapezius right	0.05	-0.21	-0.30	0.00
	Mean PPT Trapezius left	0.08	-0.30	-0.17	0.00
	Tibialis right	-0.10	-0.31	0.07	-0.15
	Tibialis left	-0.15	-0.25	-0.03	-0.10
Psychological factors
	KSQ-Aw	-0.29	0.02	0.28	-0.02
	KSQ-Dst	-0.27	0.02	0.23	-0.06
	KSQ-Si	-0.26	0.09	0.14	0.02
	HADS-A	-0.20	0.09	-0.28	0.30
	HADS-D	-0.29	0.06	-0.07	0.24
	ASI	-0.31	0.06	0.16	0.18
	PASS-20	-0.28	-0.12	0.10	0.19
	PCS	-0.32	-0.14	-0.15	0.15
	PDI	-0.20	0.12	-0.26	0.26
	FABQphysical	-0.08	-0.10	0.13	0.18
	FABQwork	-0.27	0.01	0.21	-0.13
Explained variance	R ²	0.21	0.19	0.14	0.10

Variable loadings upon the principal components (PC) in bold indicate variables of significant importance for the component. At the bottom line is given the explained variation (R²) of each significant component (PC1-4).
Abbreviations: VAS = visual analogue scale, Abbreviations: KSQ = Karolinska sleep questionnaire, KSQ-Aw = KSQ- subscale "awakening problems", KSQ- Dst = KSQ- subscale "daytime sleepiness"(denoted), KSW-Sd = KSQ- subscale "sleep disturbances", HADS = hospital anxiety and depression scale; HADS-D = depression subscale of HADS, HADS-A = anxiety subscale of HADS, ASI = anxiety sensitivity index, PASS = pain anxiety symptoms scale, PCS = pain catastrophizing scale; FABQ = fear-avoidance beliefs questionnaire, FABQphysical = subscale fear-avoidance beliefs for physical activity of FABQ, FABQwork = subscale fear-avoidance beliefs for work of FABQ, PDI = pain disability index.

ISSN: 1471-2474