Establishing a consensus on ME/CFS exclusionary illnesses

Introduction: The diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is generally reached based on meeting the criteria of a case definition and eliminating other conditions that could be causing the patient’s symptoms. Investigators in the ME/CFS field are currently confronted with 139 medical exclusionary conditions listed among the various ME/CFS case definitions. There is a need to standardize the illnesses/diagnoses that should be excluded. Methods: Exclusionary conditions were listed for several prominent ME/CFS case definitions. From this list, symptoms were also identified as exclusionary by several physicians with experience in diagnosing ME/CFS. Input was also solicited from representatives from the patient community for a consensus list of exclusionary comorbid conditions. Results: Once overlapping illnesses were eliminated, a consensus was reached on a briefer set of exclusionary conditions. The final set of exclusionary conditions is divided into 14 categories with 53 specific examples. Conclusions: It is important for ME/CFS researchers to select uniform medical conditions to exclude from their studies so that samples across different studies are consistent and generate generalizable ME/CFS findings. This list can be applied to ME/CFS case definitions in order to enhance the reproducibility of identifying patients with ME/CFS for research studies.