Prevalence and incidence of chronic fatigue syndrome in Wichita, Kansas
Authors
Reyes M, Nisenbaum R, Hoaglin DC, Unger ER, Emmons C, Randall B, Stewart JA, Abbey S, Jones JF, Gantz N, Minden S, Reeves WC
Institution
Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Public Health Service, US Department of Health and Human Services, Atlanta, GA 30333, USA
Background
Chronic fatigue syndrome (CFS) is a debilitating illness with no known cause or effective therapy. Population-based epidemiologic data on CFS prevalence and incidence are critical to put CFS in a realistic context for public health officials and others responsible for allocating resources and for practicing physicians when examining and caring for patients.
Methods
We conducted a random digit-dialing survey and clinical examination to estimate the prevalence of CFS in the general population of Wichita, Kan, and a 1-year follow-up telephone interview and clinical examination to estimate the incidence of CFS. The survey included 33,997 households representing 90,316 residents. This report focuses on 7162 respondents aged 18 to 69 years. Fatigued (n = 3528) and randomly selected nonfatigued (n = 3634) respondents completed telephone questionnaires concerning fatigue, other symptoms, and medical history. The clinical examination included the Diagnostic Interview Schedule for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, laboratory testing, and a physical examination.
Results
The overall weighted point prevalence of CFS, adjusted for nonresponse, was 235 per 100,000 persons (95% confidence interval, 142–327 per 100,000 persons). The prevalence of CFS was higher among women, 373 per 100,000 persons (95% confidence interval, 210–536 per 100,000 persons), than among men, 83 per 100,000 persons (95% confidence interval, 15–150 per 100,000 persons). Among subjects nonfatigued and fatigued for less than 6 months, the 1-year incidence of CFS was 180 per 100,000 persons (95% confidence interval, 0–466 per 100,000 persons).
Conclusions
Chronic fatigue syndrome constitutes a major public health problem. Longitudinal follow-up of this cohort will be used to further evaluate the natural history of this illness.
Publication
Arch Intern Med 2003 Jul 14; 163(13): 1530–6.
Comment from ME Research UK
This is a thorough and important study. The efforts made by the authors to confirm the diagnosis of CFS (by, for example, identifying other medical and psychiatric causes for symptoms, and inviting the entire telephone-identified CFS group for a detailed clinical examination to confirm/exclude the self-report) are particularly impressive. The overall estimate obtained is broadly in accord with previous estimates from informed sources: 200–400 per 100,000 (CMO report, UK) and 422 per 100,000 (Jason et al, Arch Intern Med 1999; 159: 2129–37). As the authors make clear, the specific estimate for women (373 per 100,000) is about one third of the prevalence estimate for breast cancer in Kansas State (1000 per 100,000), and three times the estimate for cervical cancer (100 per 100,000). Disturbingly, the median duration of illness in women was 7.3 years, a long time to be ill yet in accord with other studies of the social and medical consequences of this illness. The confidence intervals of the estimates are wide, reflecting the imprecision of estimates obtained for relatively uncommon conditions, and the heterogeneity of the patient group is problematic (always a consideration in studies of the umbrella term CFS, and the reason for efforts to devise a new working case definition. It is heartening, then, that the authors recognise the “limitations in the accuracy of case ascertainment with the current CFS case definition
” and the need to derive empirical diagnostic markers to sub-stratify CFS patients for further aetiological and treatment research. The authors say that work is underway to construct a ‘molecular profile’ of the people identified in this epidemiological study, using their peripheral blood samples for gene expression profiling (see ME Research UK report on the AACFS conference for reports from researchers using this technique). We warmly await their results.
