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 from 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.