A 5.5 year prospective study of self-reported musculoskeletal pain and of fibromyalgia in a female population: significance and natural history.

In order to investigate the significance and outcome of self-reported pain and fibromyalgia (FM) in a female population, 214 women with initially self-reported pain were interviewed and examined in 1990 and 1995. In 1990 the sample was categorised into four pain status groups: 46 individuals (21%) with nonchronic (recurrent) pain, 69 (32%) with chronic regional pain 42 (20%) with chronic multifocal pain and 57 with chronic widespread pain (CWP). The last group comprised 39 (18%) women with FM, fulfilling the American College of Rheumatology 1990 criteria. The frequency of tender points, associated symptoms called historical variables and individuals with low education increased statistically significantly with increasing pain status. In 1995, 48 women had non-chronic pain (23%), 46 (21%) chronic regional pain, 39 (18%) chronic multifocal pain and 81 (38%) CWP; of these, 71 (33%) had FM. Eleven of the 39 women initially with FM no longer fulfilled the criteria. The risk of developing CWP among the 157 individuals with initially a lower pain status was statistically higher in women with chronic multifocal pain than in women with less pain extension. Self-reported pain constitutes a continuum of pain severity and thus of clinical and social significance. The overall outcome was poor with an increase of individuals with CWP and FM. The prognosis of chronic multifocal pain, CWP and FM was especially poor. About half of the women with non-chronic pain or chronic regional pain did not deteriorate. However, because the process of developing FM started with localised pain in most cases, self-reported pain of any severity confers a risk for developing FM. Identifying possible risk factors for FM are at present under study and will be presented separately in another report.