Brurberg, Kjetil Gundro, Fønhus, Marita Sporstøl, Larun, Lillebeth et al. · BMJ open · 2014 · DOI
This study reviewed 20 different definitions doctors use to diagnose ME/CFS and examined 38 research studies that tested how well these definitions work. The researchers found that while one definition (CDC-1994/Fukuda) is used most often, no single definition has been proven to be the best. The study suggests that instead of creating more new definitions, doctors should focus on using the same definitions consistently and grouping patients by symptom patterns to predict who will improve with different treatments.
Standardized diagnostic criteria are essential for ME/CFS research and clinical care, but conflicting definitions have fragmented the field and made it difficult to compare studies or ensure patients receive consistent diagnoses. This review clarifies that rather than continuing to develop new definitions, the field should adopt consistent standards and use patient subtyping by severity and symptoms to better predict outcomes and treatment responses.
This study does not prove which case definition is 'correct' or most biologically valid, nor does it establish what causes ME/CFS. The review also does not test whether any definition reliably identifies the underlying biological mechanisms of the disease. Additionally, findings about case definition utility cannot be extrapolated to clinical settings where diagnostic practice may differ from research protocols.
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
Brurberg, Kjetil Gundro, Fønhus, Marita Sporstøl, Larun, Lillebeth, Flottorp, Signe, & Malterud, Kirsti (2014). Case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME): a systematic review.. BMJ open. https://doi.org/10.1136/bmjopen-2013-003973
BibTeX
@article{mecfsatlas-brurberg-2014-case-definitions,
author = {Brurberg, Kjetil Gundro and Fønhus, Marita Sporstøl and Larun, Lillebeth and Flottorp, Signe and Malterud, Kirsti},
title = {Case definitions for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME): a systematic review.},
journal = {BMJ open},
year = {2014},
doi = {10.1136/bmjopen-2013-003973},
note = {PubMed: 24508851},
url = {https://www.mecfsatlas.com/evidence/brurberg-2014-case-definitions},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/brurberg-2014-case-definitions
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