The Comparative Burden of Chronic Widespread Pain and Fibromyalgia in the United States.

BACKGROUND/PURPOSE: Little information exists on the comparative patient and economic burden of chronic widespread pain (CWP) and fibromyalgia (FM) in the United States.

METHODS: This multistage, observational study included an online screening survey of a large geographically diverse US sample to assess CWP status, a physician/site visit to determine FM diagnosis, and an online subject questionnaire to capture clinical characteristics, pain, health status, functioning, sleep, healthcare resource use (HRU), productivity, and costs. Based on the screener and physician evaluation, mutually exclusive groups of subjects without CWP (CWP-), with CWP but without FM (CWP+), and with confirmed FM were identified.

RESULTS: Disease burden was examined in 472 subjects (125 CWP-, 176 CWP+, 171 FM). Age, race, and ethnicity were similar across groups. Mean body mass index and number of comorbidities increased from CWP- to CWP+ to FM (P = 0.0044, P < 0.0001, respectively). From CWP- to CWP+ to FM, there were reductions in health status (EQ-5D, SF-12) and sleep outcomes (MOS-SS, SSQ) (all P < 0.05). Pain severity, interference with function (BPI-SF), and overall work impairment (WPAI:SHP) increased from CWP- to CWP+ to FM (all P < 0.0001). Higher proportions of CWP+ (52.8%) and FM subjects (62.6%) were taking pain-related prescription medications relative to CWP- subjects (32.8%; P < 0.0001). Significant differences in total direct and indirect costs across the three groups (both P < 0.0001) were observed, with highest costs among FM subjects.

CONCLUSION: Fibromyalgia subjects were characterized by the greatest disease burden with more comorbidities and pain-related medications, poorer health status, function, sleep, lower productivity, and higher costs.