Patients diagnosed with Myalgic encephalomyelitis/chronic fatigue syndrome also fit systemic exertion intolerance disease criteria

Abstract

Background: Myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS) remains undiagnosed in up to 91% of patients. Recently, the United States-based Institute of Medicine (IOM) developed new diagnostic criteria, naming it systemic exertion intolerance disease (SEID). Purpose: We examined how subjects fit SEID criteria and existing ME/CFS case definitions early in their illness. Methods: A total of 131 subjects fitting 1994 Fukuda CFS criteria at the time of study recruitment completed a survey of symptoms they experienced during their first 6 months of illness. Symptoms were drawn from SEID and existing criteria (1994 Fukuda, 2003 Canadian Consensus Criteria (CCC), and 2011 Myalgic Encephalomyelitis-International Consensus Criteria (ME-ICC)). We calculated and compared the number/percentage of subjects fitting single or combinations of case definitions and the number/percentage of subjects with SEID experiencing orthostatic intolerance (OI) and/or cognitive impairment. Results: At 6 months of illness, SEID criteria identified 72% of all subjects, similar to when Fukuda criteria (79%) or the CCC (71%) were used, whereas the ME-ICC selected for a significantly lower percentage (61%, p