This study investigated the significance and course of pain in a female population over a period of 5.5 years. 2,038 women from the general population were evaluated for their self-reported pain, history, and associated symptoms (fatigue, swelling, sleep disturbance, waking achy). 1,168 reported chronic pain, and 214 had an extensive interview and examination. 16 pain sites, and 18 tender points were examined by applying pressure with fingers. The authors also measured the intensity of fatigue, pain, and stiffness via a scale questionnaire.
In performing this study the authors established four categories for pain and patients:
 At the baseline, 46 had NCP, 69 CRP, 42 CMP, and 57 CWP. Of the 57 CWP, 39 patients met the diagnostic criteria for fibromyalgia (FM).
5.5 years later only 7 patients had no pain. The regional pain group decreased by 11%, and the widespread pain group increased by 11%. The FM subgroup increased to include 71 patients—33% of the total sample. The following charts express the differences, and how the groups changed over the years.
Condition | Percentage |
Worsened | 71 (33%) |
Same | 88 (41%) |
Improved | 55 (26%) |
The authors conclude:
"These observations indicate that the extension of pain in musculoskeletal pain syndromes tends to increase with time, and that an evolution into widespread pain is not uncommon...These findings, together with the overall increase in CWP, indicate an unfavorable outcome of chronic pain, especially if the extension exceeds regional pain."
Furthermore, the authors state that their "findings substantiate other reports...and indicate that FM is a clinical syndrome at the severe end of a continuum rather than a well-defined disease entity."
Forseth KO, Foree O, Gran JT. A 5.5 year prospective study of self-reported musculoskeletal pain and of fibromyalgia in a female population: significance and natural history. Clinical Rheumatology 1999;18:114-121.