Jason, Leonard A, McManimen, Stephanie, Sunnquist, Madison et al. · Fatigue : biomedicine, health & behavior · 2016 · DOI
This study looked at 556 ME/CFS patients from three countries to understand how doctors should diagnose this condition. The researchers found that patients fall into different groups based on their symptoms: some have chronic fatigue alone, some have fatigue with other medical reasons, and some have ME/CFS with additional symptoms like problems with exercise recovery, brain fog, and sleep issues. The groups with more specific ME/CFS symptoms were significantly more disabled than those with just general fatigue.
This study helps clarify how ME/CFS should be diagnosed by showing that different patient groups have different levels of severity and disability. Using multiple established criteria (IOM, Canadian, ME-ICC) to group patients provides evidence that more specific diagnostic definitions identify people who are significantly more impaired, which could improve clinical care and research participant selection.
This study does not prove which case definition is 'correct' or most valid—it only shows that more restrictive definitions identify more functionally impaired patients. The cross-sectional design cannot establish causation or whether these groupings represent distinct biological entities. It also does not validate these definitions against biomarkers or long-term outcomes.
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
Jason, Leonard A, McManimen, Stephanie, Sunnquist, Madison, Brown, Abigail, Furst, Jacob, Newton, Julia L, et al. (2016). Case definitions integrating empiric and consensus perspectives.. Fatigue : biomedicine, health & behavior. https://doi.org/10.1080/21641846.2015.1124520
BibTeX
@article{mecfsatlas-jason-2016-case-definitions,
author = {Jason, Leonard A and McManimen, Stephanie and Sunnquist, Madison and Brown, Abigail and Furst, Jacob and Newton, Julia L and Strand, Elin Bolle},
title = {Case definitions integrating empiric and consensus perspectives.},
journal = {Fatigue : biomedicine, health & behavior},
year = {2016},
doi = {10.1080/21641846.2015.1124520},
note = {PubMed: 27088059},
url = {https://www.mecfsatlas.com/evidence/jason-2016-case-definitions},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/jason-2016-case-definitions
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