Co-existence of chronic fatigue syndrome with fibromyalgia syndrome in thegeneral population - A controlled study

Objective: To determine the proportion of adults with fibromyalgia syndrome (FMS) in the general population who also meet the 1988 Centre for Disease Control (CDC) criteria for chronic fatigue syndrome (CFS). Methods: Seventy-four FMS cases were compared with 32 non-FMS controls with widespread pain and 23 with localized pain, all recruited in a general pop ulation survey. Results: Among females, 58.0% of fibromyalgia cases met the full criteria f or CFS, compared to 26.1% and 12.5% of controls with widespread and localiz ed pain, respectively (p = 0.0006). Male percentages were 80.0, 22.2, and z ero, respectively (p = 0.003). Compared to those with FMS alone, those meet ing the case definitions for both FMS and CFS reported a worse course, wors e overall health, more dissatisfaction with health, more non-CFS symptoms, and greater disease impact. The number of total symptoms and non-CFS sympto ms were the best predictors of co-morbid CFS. Conclusions: There is significant clinical overlap between CFS and FMS.