Fibromyalgia (FM) is a major determinant of poor health status in systemic lupus erythematosus (SLE). FM has been shown to be associated with neurally mediated hypotension (NMH) in the general population, in which effective treatments exist. We explored whether NMH was more common in SLE patients with FM than those without.
Seventy-six SLE patients (4 male, 72 female; 1 ethnic Indian, 28 African American, 47 Caucasian; mean age 40.2 +/- 9.4 yr) were recruited and their FM status ascertained using American College of Rheumatology (ACR) classification criteria. Patients who were pregnant or deconditioned were excluded. A two-stage tilt-table test was used to detect NMH. All patients completed the SF-36 Heath Status Inventory (SF-36) and the Krupp Fatigue Severity Scale (KFSS) to evaluate their quality of life. Serological markers and the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) were recorded. Medications that might interfere with testing were temporarily withheld before the tilt-table test.
The prevalence of NMH (first stage) in SLE patients was 47.9%. Seven patients had both NMH and postural orthostatic tachycardia syndrome. Two patients had borderline results with symptoms reproduced but an inadequate drop in systolic blood pressure by definition (a drop of at least 25 mmHg defines an abnormal response). Eighteen (23.7%) SLE patients had FM and 51 (67.1%) had at least one tender point (TP). The frequency of NMH (first or second stage) in SLE with FM was 58.3% compared with 69.4% in SLE without FM (odds ratio 0.62, 95% CI 0.16-2.37). SF-36 and KFSS scores were not significantly different in SLE patients with and without NMH. However, both scores were found to be associated with FM status (P<0.001 and P = 0.014), reflecting poor health status in the FM group. No confounding variable was found to be significantly associated with both NMH and FM.
NMH is common in SLE patients with a high prevalence rate. The large increase in NMH, a form of autonomic neuropathy, in SLE, has not been explained. However, NMH has no impact on quality of life above that determined by FM, and has no statistically significant association with FM status. Identification of NMH may be important in selected patients with SLE who have chronic fatigue, but NMH cannot explain the increased prevalence of FM in SLE.