Davenport, Todd E, Chu, Lily, Stevens, Staci R et al. · Work (Reading, Mass.) · 2023 · DOI
This study found that asking patients about just two specific symptoms can accurately identify post-exertional malaise (PEM), the key feature of ME/CFS. Researchers had people with ME/CFS and healthy controls exercise twice, 24 hours apart, and report their symptoms at different times. The most reliable symptoms for identifying PEM were cognitive problems (brain fog), worsening function, and loss of positive feelings or mood.
PEM is difficult to diagnose because it manifests in many different ways. This study provides clinicians with a quick, accurate screening tool using just two symptoms, potentially improving early identification and diagnosis of ME/CFS. Having a simple diagnostic marker could accelerate both clinical recognition and research enrollment.
This study does not establish causation or explain the biological mechanisms underlying PEM. The small sample size (49 ME/CFS patients) limits generalizability, and the findings need validation in independent, larger populations before they can be reliably applied in routine clinical practice. This was a controlled laboratory setting and may not reflect how PEM manifests in real-world conditions.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Davenport, Todd E, Chu, Lily, Stevens, Staci R, Stevens, Jared, Snell, Christopher R, & Van Ness, J Mark (2023). Two symptoms can accurately identify post-exertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome.. Work (Reading, Mass.). https://doi.org/10.3233/WOR-220554
BibTeX
@article{mecfsatlas-davenport-2023-two-symptoms,
author = {Davenport, Todd E and Chu, Lily and Stevens, Staci R and Stevens, Jared and Snell, Christopher R and Van Ness, J Mark},
title = {Two symptoms can accurately identify post-exertional malaise in myalgic encephalomyelitis/chronic fatigue syndrome.},
journal = {Work (Reading, Mass.)},
year = {2023},
doi = {10.3233/WOR-220554},
note = {PubMed: 36938769},
url = {https://www.mecfsatlas.com/evidence/davenport-2023-two-symptoms},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/davenport-2023-two-symptoms
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