To investigate the association of joint hypermobility (JH) and primary fibromyalgia (FM).
Eighty-eight patients admitted with widespread pain and 90 matched healthy controls were blindly evaluated according to criteria for the presence of JH and FM.
Fifty-six patients initially recognized as having FM met the American College of Rheumatology (ACR) diagnostic criteria for FM and 6 of 90 healthy controls had these criteria at the subsequent blinded examination. The frequency of JH was 8% in patients with FM and 6% in subjects without FM (p > 0.05). Interestingly, JH was found in 10 of 32 "FM" patients (31%) who had not exactly met the ACR criteria for FM. The occurrence of JH was more common in these patients compared to controls (p < 0.001). In total, 16% of patients evaluated with widespread pain had associated with JH.
Some patients who have clinical symptoms of FM but do not exactly meet the ACR criteria could in fact have JH, and these patients may be misdiagnosed as having FM. Widespread pain is associated with JH in women under age 50, with some of them fulfilling ACR tender point criteria for FM.