Background/Purpose: Few data exist on the comparative burden of chronic widespread pain (CWP) and fibromyalgia (FM) in the general population.

Methods: 8,382 nationally representative participants (≥18 years old) completed an online screener including sociodemographic questions and the London Fibromyalgia Epidemiology Study Screening Questionnaire (LFESSQ). Subjects who screened positive (bilateral pain, above/below waist, lasting ≥1 week in the past 3 months; CWP+), and a control group without CWP (CWP‑) were invited for a site visit for physician evaluation of FM including a tender point exam. Of 1,331 CWP+ and 502 CWP- subjects who consented to be scheduled for a visit, mutually exclusive groups of CWP- (n=125), CWP+ (n=176) and confirmed FM subjects based on physician evaluation (n=171) completed a visit and an online questionnaire to assess clinical characteristics and patient-reported outcomes (including Brief Pain Inventory-short form [BPI-SF], Medical Outcomes Study Sleep Scale [MOS-SS], 12-Item Short Form Health Survey v2 [SF-12], EQ-5D-3L). Statistical significance was tested at the 0.05 level across the 3 groups using ANOVA for continuous variables and chi-square or Fisher’s exact test for categorical variables.

Results: Age and race were similar among the 3 groups, but mean body mass index (kg/m²) increased from CWP- (28.8) to CWP+ (30.7) to FM (32.1) (P=.0044). Among those reporting comorbidities, the mean (SD) number increased from 2.4 (1.6) to 3.2 (2.0) and 4.9 (3.0) for CWP-, CWP+, and FM, respectively (P<.0001), with a corresponding greater prevalence of specific physical conditions (e.g. arthritis, headache/migraine, irritable bowel syndrome; all P<.003) and affective disorders (anxiety, depression; both P<.0001). Pain severity and interference with function progressively increased from CWP- to CWP+ to FM (P<.0001) (Table), including all BPI-SF interference subscales. Sleep quantity and quality significantly differed across the groups as indicated by the MOS-SS total score (Table) and subscales. The EQ-5D-3L and SF-12 showed progressive reduction in health status, and physical and mental health, respectively (Table); all SF-12 domains scores were lowest with FM followed by CWP+ and CWP- (P<.0001). Relative to CWP-, higher proportions of CWP+ and FM groups were taking pain-related prescription medications, 32.8%, 52.8% and 62.6%, respectively (P<.0001); opioids were the single most frequently reported pain medication class.

Conclusion: In a nationally representative sample, CWP+ and FM were characterized by a high disease burden relative to CWP- including more comorbidities and pain-related medications, poorer sleep, and reduced function and health status; the burden was highest with FM. Health status observed in FM was lower than has been reported for chronic conditions, such as cancer and diabetes (Luo et al. Health Outcomes Res Med.2011;e203-14).

 

Table. Comparative Burden in Subjects by Chronic Widespread Pain (CWP) and Fibromyalgia (FM) Status
Measure	Mean (standard deviation)			P-value
	CWP- (n=125)	CWP+ (n=176)	FM (n=171)
BPI-SFa
Pain Severity Index	3.0 (2.1)	4.4 (2.1)	5.5 (2.0)	<.0001
Pain Interference Index	2.5 (2.5)	4.3 (2.6)	5.8 (2.4)	<.0001
MOS-SS total scorea	32.8 (18.7)	48.2 (18.5)	59.6 (17.5)	<.0001
SF-12b
Physical Component Summary score	48.1 (10.8)	38.9 (11.0)	33.7 (10.5)	<.0001
Mental Component Summary score	49.1 (10.4)	44.9 (10.8)	40.4 (10.8)	<.0001
EQ-5D-3Lb
Health state valuation	0.85 (0.13)	0.73 (0.18)	0.61 (0.21)	<.0001
Overall health status rating	79.8 (16.0)	68.7 (18.8)	58.7 (20.0)	<.0001
aHigher score=worse outcomes; blower score=worse outcomes

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparative-burden-of-chronic-widespread-pain-and-fibromyalgia-in-the-us-population/