Tokumasu, Kazuki, Honda, Hiroyuki, Sunada, Naruhiko et al. · Medicina (Kaunas, Lithuania) · 2022 · DOI
This study examined patients with long COVID who developed ME/CFS, a serious condition causing extreme fatigue and worsening after activity. Researchers found that about 17% of long COVID patients met standardized medical criteria for ME/CFS, with fatigue and post-exertional malaise being the most common symptoms. Interestingly, men and women were affected equally in this group, which differs from typical ME/CFS patterns.
This study provides rare rigorous data on ME/CFS diagnosed using standardized clinical criteria in long COVID patients, rather than relying on patient-reported symptoms alone. Understanding ME/CFS prevalence and specific symptom profiles in post-COVID populations helps clinicians recognize this serious condition earlier and supports research into shared pathophysiological mechanisms between viral infections and ME/CFS.
This study does not establish causality between COVID-19 severity and ME/CFS development—it only observes correlation. The retrospective design cannot determine whether acute infection severity directly causes ME/CFS or if other unmeasured factors contribute. Findings from a single Japanese clinic may not generalize to other populations or healthcare systems.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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