Fibromyalgia and Widespread Pain Weakly Associated With Mortality

There is a weak association of fibromyalgia and widespread pain with risk for mortality, and this association can also be observed with other specific rheumatic disorders, including rheumatoid arthritis (RA) and noninflammatory rheumatic disorders (NIRMD), according to study results published in Seminars in Arthritis and Rheumatism.

In this observational study, researchers enrolled patients with rheumatic diseases aged between 21 and 103 years who were referred by rheumatologists to the National Data Bank for Rheumatic Diseases (n=35,248). Patients with RA (n=26,458), NIRMD (n=5167), and clinical fibromyalgia (n=3659) completed detailed health assessment questionnaires (HAQs) on a semiannual basis between July 1999 and December 2014. Researchers queried the National Death Index for data on death; all other variables were self-reported.

Results showed that death rates per 1000 person-years were 25.1 for all patients (95% CI, 24.5-25.6), 27.1 for patients with RA (95% CI, 26.4-27.7), 25.5 for patients with NIRMD (95% CI, 24.1-27.0), and 10.6 for patients with clinical fibromyalgia (95% CI, 9.6-11.8). The standardized mortality ratio was substantially greater for the RA group (1.26; 95% CI, 1.23-1.29) than it was for the NIRMD group (0.72; 95% CI, 0.69-0.77) and clinical fibromyalgia group (0.76; 95% CI, 0.68-0.84). However, the relative risks (RRs) for the 3 disorders were similar and increased above unity: 1.52 for patients with RA (95% CI, 1.43-1.61), 1.43 for patients with NIRMD (95% CI, 1.24-1.66), and 1.41 for patients with clinical fibromyalgia (95% CI, 1.14-1.75), indicating that criteria positive fibromyalgia is associated with increased risk for mortality regardless of associated or underlying diagnosis. The factors most strongly associated with fibromyalgia criteria positivity were age ≥65 years (RR, 9.11; 95% CI, 7.17-11.58), current smoking status (RR, 2.10; 95% CI, 1.37-1.50), high levels of HAQ (RR, 5.72; 95% CI, 5.11-6.42), and household income below the median (RR, 1.90; 95% CI, 1.48-2.49). Important protective factors included being women and married (0.54; 95% CI, 0.42-0.70). Multivariable model analysis indicated a disagreement between functional severity and fibromyalgia status, in favor of the effect of HAQ values.

In terms of cause-specific mortality, of the 20 cause-specific conditions, 5 were statistically significant, with an increased risk for death from suicides, accidents, diabetes, and hypertension-related disorders (odds ratios [ORs], 3.01, 1.45, 1.78, and 2.12, respectively). However, it was observed that patients with fibromyalgia were less likely to die from cancer (OR, 0.77).

Limitations included the reliance of the study on the willingness of enrolled patients with rheumatic diseases to participate in surveys, the researchers’ inability to examine complex drug use and drug continuation and switching, and the fact that patient status may have changed to fibromyalgia positive or negative during the course of the study.

“Clinical [fibromyalgia] can be split into criteria positive and criteria negative states, but positive associations with mortality only occur in criteria positive states,” the researchers concluded. “When covariates are added to multivariable analyses, the effect of [fibromyalgia] criteria diagnosis remains, but is reduced. Finally, the effect of [fibromyalgia] and [widespread pain] on mortality is weak, explaining <4% of explained variance. On an etiologic basis, it remains uncertain whether fibromyalgia as an entity contributes to mortality or is just conduit for underlying associated physical and mental stressors.”

Reference

Wolfe F, Ablin J, Baker JF, et al. All-cause and cause-specific mortality in persons with fibromyalgia and widespread pain: An observational study in 35,248 persons with rheumatoid arthritis, non-inflammatory rheumatic disorders and clinical fibromyalgia [published online February 16, 2020]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2020.02.005