Brown, Abigail, Jason, Leonard A · Journal of health psychology · 2020 · DOI
This study looked at research from multiple studies to understand how common post-exertional malaise (PEM) is in people with ME/CFS. Post-exertional malaise is when symptoms get worse after physical or mental activity. The researchers found that people with ME/CFS are about 10 times more likely to experience post-exertional malaise than people without the condition, suggesting it is a key feature of ME/CFS.
This meta-analysis provides robust evidence that post-exertional malaise is a core distinguishing feature of ME/CFS, which could improve diagnostic accuracy and clinical recognition. Understanding that PEM is significantly more common in ME/CFS than in healthy populations validates the patient experience and emphasizes the importance of including this symptom in case definitions used by healthcare providers worldwide.
This study does not establish the biological mechanisms causing post-exertional malaise or why it occurs in ME/CFS. It also does not prove that PEM is unique to ME/CFS, only that it is much more common in this population than in controls. Additionally, as a meta-analysis relying on previously published studies, the quality of evidence depends on the individual studies included.
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
Brown, Abigail & Jason, Leonard A (2020). Meta-analysis investigating post-exertional malaise between patients and controls.. Journal of health psychology. https://doi.org/10.1177/1359105318784161
BibTeX
@article{mecfsatlas-brown-2020-meta-analysis,
author = {Brown, Abigail and Jason, Leonard A},
title = {Meta-analysis investigating post-exertional malaise between patients and controls.},
journal = {Journal of health psychology},
year = {2020},
doi = {10.1177/1359105318784161},
note = {PubMed: 29974812},
url = {https://www.mecfsatlas.com/evidence/brown-2020-meta-analysis},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/brown-2020-meta-analysis
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