De Becker, P, McGregor, N, De Meirleir, K · Journal of internal medicine · 2001 · DOI
This study looked at 2,073 patients with chronic fatigue to understand how well two common diagnostic criteria (Fukuda and Holmes) identify ME/CFS. The researchers found that the Holmes criteria selected patients with more severe symptoms, while the Fukuda criteria included a broader group with milder cases. Adding or removing certain symptoms from the current diagnostic criteria could help doctors better identify who truly has ME/CFS.
This study directly addresses the clinical heterogeneity problem in ME/CFS by showing that different diagnostic criteria select populations with meaningfully different symptom severity profiles. For patients, this explains why diagnostic consistency varies globally and supports the need for refined diagnostic criteria. For researchers, it provides empirical evidence that symptom severity and prevalence patterns could strengthen case definitions to reduce diagnostic confusion.
This study does not prove which diagnostic criteria is 'correct' or best for identifying true ME/CFS cases, nor does it establish causation for any symptoms. It also does not validate the proposed additional symptoms in independent populations, and the cross-sectional design cannot determine whether symptom severity differences reflect true biological heterogeneity or simply different thresholds for seeking tertiary care.
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
De Becker, P, McGregor, N, & De Meirleir, K (2001). A definition-based analysis of symptoms in a large cohort of patients with chronic fatigue syndrome.. Journal of internal medicine. https://doi.org/10.1046/j.1365-2796.2001.00890.x
BibTeX
@article{mecfsatlas-de-becker-2001-definition-based,
author = {De Becker, P and McGregor, N and De Meirleir, K},
title = {A definition-based analysis of symptoms in a large cohort of patients with chronic fatigue syndrome.},
journal = {Journal of internal medicine},
year = {2001},
doi = {10.1046/j.1365-2796.2001.00890.x},
note = {PubMed: 11555128},
url = {https://www.mecfsatlas.com/evidence/de-becker-2001-definition-based},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/de-becker-2001-definition-based
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