Contrasting chronic fatigue syndrome versus myalgic encephalomyelitis/chronic fatigue syndrome

BACKGROUND: Much debate is transpiring regarding whether chronic fatigue syndrome (CFS) and myalgic encephalomyelitis (ME) are different illnesses. Several prior studies that compared the Fukuda et al. CFS criteria to the Canadian ME/CFS criteria found that the Canadian criteria identified patients with more functional impairments and greater physical, mental, and cognitive problems than those who met Fukuda et al. criteria.3,4 These samples were located in the Chicago metropolitan area, so the results could not be generalized to other locations. In addition, past studies used a symptom questionnaire that was not specifically developed to tap the Canadian criteria. PURPOSE: The present comparative study of CFS and ME/CFS criteria was intended to correct the methodological problems of prior studies. METHODS: This article used data from three distinct samples to compare patients who met criteria for the ME/CFS Canadian clinical case definition 1 to those who met the Fukuda et al. CFS case definition.2. RESULTS: Findings indicated that fewer individuals met the Canadian criteria than the Fukuda et al. criteria. Those who met the Canadian criteria evidenced more severe symptoms and physical functioning impairment. CONCLUSIONS: Future research should continue to compare existing case definitions and determine which criteria best select for this illness.