BY Leonard A. Jason in Oxford University Press’s Blog.
Current estimates from the Centers for Disease Control and Prevention (CDC) of the number of people in the United States with chronic fatigue syndrome (CFS) increased from about 20,000to as many as four million within a ten-year period. If this were true, we would be amidst an epidemic of unprecedented proportions. I believe that these increases in prevalence rates can be explained by unreliable case definitions. For example, in 1994, the CDC’s case definition did not require patients to have core symptoms of the CFS. Making matters worse, in 2005, in an effort to operationalize their inadequate case definition, the CDC broadened the case definition so that ten times as many patients would be identified.
Even though these estimates were challenged as bringing into the CFS case definition many who did not have this illness such as Major Depressive Disorder, as late as 2016, the CDC re-affirmed the merit in this broader case definition.
Another misguided effort occurred in 2015, when the Institute of Medicine (IOM) developed a revised clinical case definition that at least did specify core symptoms, but unfortunately also eliminated almost all exclusionary conditions, so those who had had previously been diagnosed with other illnesses such as Melancholic Depressive Disorders, could now be classified as meeting the new IOM criteria.
This case definition has the unfortunate consequence of again broadening the types of patients that will now be identified, thus their effort also will inappropriately select many patients with other diseases as meeting the new IOM criteria. Making matters even worse, the clinical case definition was not designed to be used for research purposes, but it is clearly being used in this way, and one group of researchers has already inaccurately reported that the new clinical case definition is as effective at selecting patients as research case definitions.
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