Underdiagnosis of myalgic encephalomyelitis/chronic fatigue syndrome-like illness in a large integrated healthcare system -- Kaiser Permanente Northern California, 2022-2023

BackgroundSurveillance of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a chronic, debilitating multisystem illness, is challenging because ME/CFS can be under-recognized in healthcare settings. MethodsUsing a population-based panel study of 9,820 adult members of Kaiser Permanente Northern California (KPNC), a large, integrated healthcare system, we compared survey-defined ME/CFS-like illness with presence of an ME/CFS diagnosis in the electronic health record (EHR) to evaluate ME/CFS underdiagnosis. ResultsOf those with survey-defined ME/CFS-like illness, an estimated 97.8% (95% confidence interval [CI] 97.1%-98.4%) did not have an ME/CFS diagnosis in the EHR. The group without EHR diagnosis was younger, less likely to identify as white non-Hispanic, and more likely to have developed fatigue in the past three years than the EHR diagnosed group. Both diagnosed and undiagnosed ME/CFS-like illness groups had significantly impaired physical, cognitive, and social functioning, and significantly worse mental health and anxiety than those without ME/CFS-like illness. ConclusionME/CFS is underdiagnosed in the Kaiser Permanente Northern California healthcare system. Enhanced syndromic surveillance that characterizes patients with ME/CFS who have not been diagnosed has the potential to increase timely recognition of ME/CFS.