Aspects of Fibromyalgia in the General Population: Sex, Pain Threshold, and Fibromyalgia Symptoms

Objective: To investigate relationships between sex, pain threshold and fibromyalgia (FM) symptoms in the general population.

Methods: Data were obtained from a randomized populations survey of 3,006 persons in Wichita, KS and a subsample of 391 who completed a detailed interview and had an examination. Tender point counts, dolorimetry scores, clinical and psychological variables were measured.

Results: Dolorimetry scores were 2.04 kg/cm (1.42-2.66) lower in women than men, and women were almost 10 times more likely to have 11 tender points [OR 9.6 (2.00-46.3)] than men. Women are also more likely to have FM symptoms than men: "Pain all over," [OR 3.94 (1.34-11.38)], sleep disturbance [OR 3.06 (1.45-6.46)], fatigue [OR 4.52 (2.03-10.09)], and irritable bowel syndrome [OR 5.23 (1.83-14.96)]. Tender point counts are more correlated with FM symptoms than dolorimetry scores.

Conclusion: Symptoms of FM are correlated with pain threshold in the general population, but tender point counts correlate better than dolorimetry. These 2 measures of pain threshold assay different but overlapping factors. Pain threshold is lower in women; and women have more FM symptoms. Decreased pain threshold correlates with all of the symptoms of FM, even in those who do not meet criteria for the syndrome. This suggests that decreased pain threshold, as measured by the tender point counts, is an intrinsically important aspect of patient distress, regardless of the extent and kind of concomitant disease; and that much can be learned about patients by employing this examination.