PREVALENCE OF FATIGUE AND CHRONIC FATIGUE SYNDROME IN A PRIMARY-CARE PRACTICE

Background: Our goals were to determine the prevalence of unusual, deb ilitating fatigue and the frequency with which it was associated with the chronic fatigue syndrome (CFS) or other physical or psychological illness in an outpatient clinic population. Methods: We prospectively evaluated a cohort of 1000 consecutive patients in a primary care clin ic in an urban, hospital-based general medicine practice. The study pr otocol included a detailed history, physical examination, and laborato ry and psychiatric testing. Results: Five patients who came because of CFS studies were excluded. Of the remaining 995, 323 reported fatigue , and 271 (27%) complained of at least 6 months of unusual fatigue tha t interfered with their daily lives. Of the 271, self-report or record review revealed a medical or psychiatric condition that could have ex plained the fatigue in 186 (69%). Thus, 85 (8.5%) of 995 patients had a debilitating fatigue of at least 6 months' duration, without apparen t cause. Of these patients, 48 refused further evaluation, and II were unavailable for follow-up; 26 completed the protocol. Three of the 26 were hypothyroid, and one had a major psychiatric disorder. Of the re maining 22 patients, three met Centers for Disease Control and Prevent ion criteria for CFS, four met British criteria, and 10 met the Austra lian case definition. The point prevalences of CFS were thus 0.3% (95% confidence interval ICI], O% to 0.6%), 0.4% (95% CI, O% to 0.8%), and 1.0% (95% CI, 0.4% to 1.6%) using the Centers for Disease Control and Prevention, British, and Australian case definitions, respectively. T hese estimates were conservative, because they assumed that none of th e patients who refused evaluation or were unavailable for follow-up wo uld meet criteria far CFS. Conclusions: While chronic, debilitating fa tigue is common in medical outpatients, CFS is relatively uncommon. Pr evalence depends substantially on the case definition used.