Jason, Leonard A, Brown, Abigail, Evans, Meredyth et al. · Fatigue : biomedicine, health & behavior · 2013 · DOI
This study compared two different sets of diagnostic criteria used to identify ME/CFS patients. Researchers found that the Canadian criteria are stricter and identify patients who tend to be more severely affected, while the older Fukuda criteria cast a wider net. This suggests that the criteria used to diagnose someone with ME/CFS can significantly affect who gets identified as having the condition.
Understanding which diagnostic criteria best identify ME/CFS patients is crucial for ensuring affected individuals receive appropriate recognition and treatment. This study demonstrates that case definition choice directly impacts disease severity profiles, which has important implications for patient care, research enrollment, and how healthcare providers understand the condition. The findings suggest that stricter criteria may better identify the most severely affected patients who need intensive clinical attention.
This study does not prove that ME and CFS are different illnesses, only that different diagnostic criteria identify different patient populations with varying severity levels. The study cannot determine causation—it shows an association between diagnostic criteria and severity but does not explain why this difference exists or whether it reflects true biological differences. Additionally, being cross-sectional, it cannot establish whether severity differences persist over time or predict disease progression.
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, Brown, Abigail, Evans, Meredyth, Sunnquist, Madison, & Newton, Julia L (2013). Contrasting Chronic Fatigue Syndrome versus Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.. Fatigue : biomedicine, health & behavior. https://doi.org/10.1080/21641846.2013.774556
BibTeX
@article{mecfsatlas-jason-2013-contrasting-chronic,
author = {Jason, Leonard A and Brown, Abigail and Evans, Meredyth and Sunnquist, Madison and Newton, Julia L},
title = {Contrasting Chronic Fatigue Syndrome versus Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.},
journal = {Fatigue : biomedicine, health & behavior},
year = {2013},
doi = {10.1080/21641846.2013.774556},
note = {PubMed: 23914329},
url = {https://www.mecfsatlas.com/evidence/jason-2013-contrasting-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/jason-2013-contrasting-chronic
Contribute
Private, reviewed by a human. Not a public comment thread.