Development and preliminary evaluation of a short self-report measure of generalized pain hypersensitivity

Figures & data

Table 1 Patient characteristics

	FM (n=98)	RA (n=114)	P-value
Female, n (%)	88/98 (89.8)	76/114 (66.7)	<0.001
Age (years), mean (SD)	45.1 (11.6)	60.1 (12.1)	<0.001
Disease duration (years), median (IQR)	9.0 (3.0–15.5)	7.5 (2.0–17.3)	0.626
Education, n (%)			0.593
Low	20/96 (20.8)	29/111 (26.1)
Medium	41/96 (42.7)	41/111 (36.9)
High	35/96 (36.5)	41/111 (36.9)
Current smoking (yes), n (%)	23/97 (23.7)	22/111 (19.8)	0.497
Current use of alcohol (yes), n (%)	54/98 (55.1)	72/111 (64.9)	0.150
Painkillers, self-reported current
Conventional (yes), n (%)	83/97 (85.6)	57/110 (51.8)	<0.001
Neuropathic (yes), n (%)	18/96 (18.8)	0/110 (0.0)	<0.001
Pain intensity (0–10), mean (SD)
Current pain	6.7 (1.7)	3.1 (2.6)	<0.001
Strongest pain, last 4 weeks	8.1 (1.3)	4.5 (3.0)	<0.001
Average pain, last 4 weeks	6.9 (1.5)	3.6 (2.6)	<0.001
PainDetect score, mean (SD)	20.5 (6.7)	9.7 (6.8)	<0.001
Unlikely, n (%)	17/95 (17.9)	70/109 (64.2)	<0.001
Possible, n (%)	14/95 (14.7)	28/109 (25.7)	<0.001
Likely, n (%)	64/95 (67.4)	11/109 (10.1) 20/109	<0.001
FM-survey criteria positive, n (%)	84/95 (88.4)	20/109 (18.3)	<0.001
HAQ-DI (0–3), mean (SD)	1.2 (0.6)	0.8 (0.7)	<0.001
SF36 PCS (0–100), mean (SD)	30.2 (7.7)	40.6 (10.2)	<0.001
SF36 MCS (0–100), mean (SD)	41.0 (12.4)	51.2 (10.9)	<0.001

Abbreviations: FM, fibromyalgia; HAQ-DI, Health Assessment Questionnaire – disability index; MCS, mental component summary; PCS, physical component summary; RA, rheumatoid arthritis; SF36, short-form health survey.

Table 2 Item scores and Mokken-scale analysis

	Mean (SD)	Hi (SE)	Monotonicity			Invariant item ordering
			Checks	Violations	Significant violations	Checks	Violations	Significant violations
1. Pain from light touch (eg, from a pat on the back or handshake)	1.53 (1.15)	0.64 (0.04)	37	0	0	27	0	0
2. Pain from friction on skin (eg, from clothing or the wind)	0.97 (1.16)	0.70 (0.04)	24	0	0	29	0	0
3. Pain from heat or cold that most people would not experience as painful (eg, from cold water or holding cold objects)	1.46 (1.27)	0.69 (0.06)	29	0	0	27	0	0
4. Pain that lasts longer than with most other people	2.02 (1.35)	0.65 (0.07)	41	0	0	28	0	0
5. Pain that arises only later and that wouldn’t arise in most other people (eg, hours later or the next day after exertion, such as walking)	2.20 (1.35)	0.65 (0.04)	46	20	0	28	0	0
6. Unusually intense experiences of pain (eg, nausea or gasping for air)	1.14 (1.42)	0.64 (0.06)	30	0	0	27	0	0
7. Pain that also spreads to other parts of the body (eg, pain in the hand that spreads to the underarm when holding objects)	1.81 (1.37)	0.64 (0.04)	44	2	0	28	0	0

Table 3 Spearman correlations with GPQ total score

	r	P-value
FM-survey criteria positive	0.718	<0.001
PainDetect total score	0.870	<0.001
Pain intensity	0.805	<0.001
Current pain (0–10)	0.755	<0.001
Strongest pain last 4 weeks (0–10)	0.789	<0.001
Average pain last 4 weeks (0–10)	0.724	<0.001
SF36 PCS (0–100)	–0.616	<0.001
SF36 MCS (0–100)	–0.749	<0.001
HAQ-DI (0–3)	0.718	<0.001

Abbreviations: FM, fibromyalgia; GPQ, generalized pain questionnaire; HAQ-DI, Health assessment Questionnaire – disability index; MCS, mental component summary; PCS, physical component summary; SF36, Short Form health survey.

Figure 1 ROC curve of the GPQ for classifying patients with FM vs RA.

Abbreviations: FM, fibromyalgia; GPQ, generalized pain questionnaire; RA, rheumatoid arthritis; ROC, receiver-operating characteristic.

Table 4 Univariate and multivariate associations with FM

Predictors	OR (95% CI)	P-value	Wald (df=1) test	HL χ^2 test	Nagelkerke R^2
Univariate associations
GPQ total score >10	13.74 (6.91–27.33)	<0.001	55.85
Female sex	4.40 (2.06–9.42)	<0.001	14.55
Age <50 years	10.81 (5.64–20.72)	<0.001	51.34
Clinically relevant pain	19.65 (7.81–49.47)	<0.001	40.00
Multivariate associations
Step 1				4.622, P=0.099	0.373
Female sex	3.31 (1.41–7.78)	0.006	7.52
Age <50 years	9.71 (5.00–18.86)	<0.001	45.06
Step 2				5.804, P=0.214	0.584
Female sex	2.80 (0.91–8.64)	0.073	3.21
Age <50 years	11.02 (4.76–25.53)	<0.001	31.37
GPQ total score >10	13.77 (5.96–31.81)	<0.001	37.71
Step 3				2.826, P=0.832	0.606
Female sex	2.70 (0.84–8.64)	0.095	2.78
Age <50 years	10.59 (4.34–25.85)	<0.001	26.91
GPQ total score >10	6.26 (2.25–17.41)	<0.001	12.38
Clinically relevant pain	4.73 (1.36–16.54)	0.015	5.93

Abbreviations: FM, fibromyalgia; HL, Hosmer–Lemeshow.