A Constructive Debate With the CDC on the Empirical Case Definition of Chronic Fatigue Syndrome

Abstract

The Centers for Disease Control and Prevention (CDC) estimates of the prevalence of chronic fatigue syndrome (CFS) have dramatically increased over the past 20 years, from 0.002% to 2.54%. Once considered a rare disorder, CFS is now characterized as a more common chronic health condition, with prevalence numbers suggesting that more than 4 million people in the United States have it. The authors’ research group proposes that selection criteria for CFS cases have broadened and provides data indicating 38% of those with a Major Depressive Disorder were misclassified as having CFS under the new CDC empirical case definition. The authors respond to concerns cited in Reeves, Gurbaxani, Lin, and Unger (2009). Given the importance of standardizing procedures for identifying CFS, more research is needed using different criteria on samples of patients with CFS and other illnesses. The erroneous inclusion of people with primary psychiatric conditions in CFS samples has detrimental consequences for interpreting epidemiologic and etiological findings.