Background: Fibromyalgia syndrome (FMS) is characterized by widespread persistent musculoskeletal pain. Mostly prevalent among White women, little is known about FMS in other population cohorts. This study examined secondary data of a racially diverse sample of women with FMS that were collected as part of a randomized controlled clinical trial that examined the effect of a complementary therapy intervention over the course of a 10-week guided imagery intervention to identify demographic, social, or economic differences in self-reported pain. Materials and Methods: The Brief Pain Inventory (BPI), which measures pain severity and interference, was administered to 72 women (21 Black and 51 Whites) at baseline, 6 and 10 weeks. Student's t tests and time series regression models examined racial difference in pain dimensions and treatment response. Regression models accounted for age, race, income, duration of symptoms, treatment group, pain at baseline, smoking, alcohol use, comorbid conditions, and time. Results: Black women experienced significantly higher pain severity (β = 5.52, standard deviation [SD] = 2.13) and interference (β = 5.54, SD = 2.74) than Whites (severity β = 4.56, SD = 2.08; interference β = 4.72, SD = 2.76) (interference: t = 1.92, p = 0.05; severity: t = 2.95, p = 0.00). Disparities persisted over time. Controlling for differences in age, income, and previous pain levels, Black women had 0.26 (standard error [SE] = 0.065) higher pain severity and 0.36 (SE = 0.078) higher interference than Whites. Low-income earners also experienced 2.02 (SE = 0.38) and 2.19 (SE = 0.46) higher pain severity and interference, respectively, than other earners. Results were robust to inclusion of comorbidities. Conclusions: Black women and low-income earners experienced significantly higher levels of pain severity and interference and a lower dose response to the intervention. Differentials were robust to inclusion of demographic, health, and behavioral characteristics. Findings suggest that external factors may contribute to pain perception among women with FMS.
Keywords: fibromyalgia; health disparities; pain; racial difference.