Fibromyalgia syndrome (FM) and nonarticular tenderness in relatives of patients with FM

Objective. To determine the prevalence of fibromyalgia (FM) and to assess nonarticular tenderness in relatives of patients with FM. Methods. Thirty female patients with FM randomly chosen and 117 of their close relatives (parents, brothers, sisters, children, husbands) were assessed for nonarticular tenderness. A count of 18 tender points was conducted by thumb palpation, and tenderness thresholds were assessed by dolorimetry at 9 tender sites. FM was diagnosed according to the 1990 American College of Rheumatology criteria. Results. The prevalence of FM among blood relatives of patients with FM was 26%, and among their husbands 19%. FM prevalence in male relatives was 14%, and in female relatives 41%. The mean tender point counts of male and female young relatives was significantly higher than that of controls: 6.1 vs 0.2 (p < 0.01), and 4.4 vs 0.4 (p < 0.01), respectively. Similarly, adult relatives had considerably higher mean tender point counts than controls: 4.0 vs 0.04 (p < 0.01) and 10.3 vs 0.28 (p < 0.01), respectively, for males and females. Conclusion. Relatives of patients with FM have a higher prevalence of FM and are more tender than the general population, as recently reported and shown in a healthy control group. This finding can be attributed to genetic and environmental factors.