Objective: To estimate the risk of developing fibromyalgia (FM) in women with self-reported pain and to estimate the relative risk of a series of variables.
Methods: As part of a population study, 214 women with self-reported pain were interviewed and examined in 1990 and 1995. In 1990, 39 of these women fulfilled the American College of Rheumatology criteria for FM. The other 175 women represented a continuum of pain extent from nonchronic pain to chronic widespread pain, and were assessed as individuals at risk for developing FM. Potential risk factors for FM were registered in 1990 and analyzed by bivariate and multiple statistical methods in the total sample and also in a subgroup of 115 women with limited pain.
Results: Forty-three (25%) women developed FM. Having > or = 4 associated symptoms, pain of > or = 6 years' duration, back pain, alternately hard/loose stools, and self-assessed depression were found to be predictors. Pain in the lower arm and a feeling of swelling were more weakly associated. In women with limited pain, pain > or = 6 years' duration, > or = 4 associated symptoms, not feeling refreshed in the morning, and paresthesia were found to be predictors. A weaker association was found with self-assessed depression and a lack of formal education.
Conclusion: A high cumulative incidence of FM was found and a diversity of predictors for FM were identified in the total sample and also in women with limited pain. Of the variables that were part of the FM syndrome, back pain predicted FM, while tender points and pain in the neck did not. Moreover, > or = 4 associated symptoms, self-assessed depression, and longlasting pain were shown to be important predictors.