Psychological Characteristics in Patients with Chronic Complex Regional Pain Syndrome: Comparisons with Patients with Major Depressive Disorder and Other Types of Chronic Pain

Figures & data

Figure 1 Flow chart of the study process.

Abbreviations: CRPS, chronic regional pain syndrome; MDD, major depressive disorder; MMPI-2, Minnesota Multiphasic Personality Inventory-2.

Table 1 Demographic and Clinical Characteristics of Patients with Chronic Pain

Variables	CRPS (n = 76)	Other Chronic Pain (n = 95)	χ^2/t	p
Age (years)^a	36.05 ± 13.02	41.65 ± 14.43	−2.63	0.009
Sex (Male/Female)	41/35	40/55	2.37	0.123
Educational level^b			2.59	0.629
Primary	3 (3.9%)	3 (3.2%)	1.36	0.713
Secondary	5 (6.6%)	10 (10.5%)
High level	42 (55.3%)	46 (48.4%)
Degree	26 (34.2%)	36 (37.9%)
Marital status, married^b	37 (48.6%)	50 (52.3%)	1.15	0.561
Pain location
Lower Extremity	48	23
Upper Extremity	44	25
Hip and Pelvis	3	8
Low back	0	28
Back	2	15
Whole body	4	11
Pain Severity (Visual Analogue Scale)^a	7.01 ± 1.76	5.43 ± 2.48	4.68	<0.001
Duration of pain symptom (years)^a	2.65 ± 2.70	3.12 ± 5.09	−0.72	0.468
Co-morbid psychiatric diagnosis^b	25 (32.9%)	37 (38.9%)	0.66	0.413
Beck Depression Inventory-II^a	24.73 ± 14.70	26.74 ± 13.40	−0.89	0.374
State-Trait Anxiety Inventory-State^a	59.87 ± 14.31	59.62 ± 14.42	0.11	0.911
State-Trait Anxiety Inventory-Trait^a	57.36 ± 15.32	57.64 ± 13.27	–0.12	0.903

Notes: ^aData given as mean ± standard deviation. ^bData given as number (%). The Student’s t-tests were applied for the comparison of means and Pearson’s χ² tests were applied for the comparison of proportions.

Abbreviation: CRPS, chronic regional pain syndrome.

Table 2 Scores on the Minnesota Multiphasic Personality Inventory-2 Scales of the Three Patient Groups and Normal Control Group

Scale	A. CRPS (n = 76)	B. Other Chronic Pain (n = 95)	C. MDD (n = 66)	D. Normal Control (n = 171)	F (df)	p	Post hoc
L	51.77 ± 11.72	49.66 ± 9.34	45.78 ± 8.86	51.55 ± 10.02	6.00 (3, 404)	0.001	C < A = D
F	49.82 ± 9.55	51.28 ± 11.62	58.12 ± 12.08	50.01 ± 9.38	10.66 (3, 404)	<0.001	A = B = D < C
K	51.00 ± 11.52	50.47 ± 10.35	45.12 ± 7.99	50.53 ± 10.05	5.49 (3, 404)	0.001	C < A = B = D
Hs	62.96 ± 11.85	64.01 ± 10.73	61.00 ± 10.48	50.00 ± 9.85	49.97 (3, 404)	<0.001	D < A = B = C
D	63.73 ± 13.60	66.41 ± 13.79	75.54 ± 10.91	49.71 ± 9.48	95.66 (3, 404)	<0.001	D < A = B < C
Hy	62.30 ± 11.50	63.72 ± 10.55	61.75 ± 9.57	50.32 ± 10.79	45.01 (3, 404)	<0.001	D < A = B = C
Pd	53.69 ± 11.15	56.33 ± 12.15	59.63 ± 10.05	51.07 ± 11.06	10.85 (3, 404)	<0.001	A < C, D < B = C
Mf	47.40 ± 9.48	47.98 ± 10.11	49.04 ± 11.23	50.33 ± 9.45	2.01 (3, 404)	0.112
Pa	55.02 ± 13.98	56.25 ± 12.99	62.10 ± 14.37	49.63 ± 9.75	18.20 (3, 404)	<0.001	D < A < C, D < B
Pt	55.71 ± 13.03	60.48 ± 12.91	71.36 ± 11.61	49.87 ± 10.37	57.23 (3, 404)	<0.001	D < A = B < C
Sc	54.51 ± 13.70	57.51 ± 13.19	62.80 ± 11.73	50.34 ± 10.40	19.40 (3, 404)	<0.001	A = B < C, D < B
Ma	50.94 ± 10.95	49.07 ± 9.70	46.25 ± 9.73	49.90 ± 10.02	2.89 (3, 404)	0.035
Si	50.47 ± 13.41	55.53 ± 13.41	68.48 ± 11.22	49.66 ± 9.45	44.90 (3, 404)	<0.001	A < C, D < B < C

Note: Data given as mean ± standard deviation. ANOVA test was applied for the comparison of means and followed by the Scheffe’s post hoc test for multiple comparisons.

Abbreviations: CRPS, chronic regional pain syndrome; MDD, major depressive disorder; L, Lie; F, Infrequency; K, Correction; Hs, Hypochondriasis; D, Depression; Hy, Hysteria; Pd, Psychopathic deviate; Mf, Masculinity–Femininity; Pa, Paranoia; Pt, Psychasthenia; Sc, Schizophrenia; Ma, Hypomania; Si, Social introversion.

Figure 2 Mean T scores on the Minnesota Multiphasic Personality Inventory-2 scales among 4 groups.

Abbreviations: CRPS, chronic regional pain syndrome; L, Lie; F, Infrequency; K, Correction; Hs, Hypochondriasis; D, Depression; Hy, Hysteria; Pd, Psychopathic deviate; Mf, Masculinity–– emininity; Pa, Paranoia; Pt, Psychasthenia; Sc, Schizophrenia; Ma, Hypomania; Si, Social introversion.

Table 3 Stepwise Linear Regression Analysis of the Variables Associated with the Pain Severity in Patients with Chronic Pain (n = 171)

Variables	VAS Score		Corrected R^2
	B (SE)	p
CRPS versus other chronic pain	2.82 (0.441)	<0.001	0.143
BDI-II	0.038 (0.013)	0.005	0.181
MMPI-2, Mf score	−0.054 (0.019)	0.017	0.211

Note: The model is adjusted for diagnosis, age, sex, educational level, marriage, symptom duration, scores on the MMPI-2, BDI-II, and STAI.

Abbreviations: VAS, visual analog scale; CRPS, complex regional pain syndrome; BDI-II, Beck Depression Inventory-II; MMPI-2, Minnesota Multiphasic Personality Inventory-2; Mf, Masculinity–Femininity.