Nacul, Luis C, Lacerda, Eliana M, Pheby, Derek et al. · BMC medicine · 2011 · DOI
This study looked at how many people in three regions of England have ME/CFS by checking medical records and asking doctors directly about their patients. Depending on which diagnostic criteria they used, between 0.03% and 0.2% of adults had ME/CFS—meaning roughly 1 in 500 to 1 in 3,300 people. The study shows ME/CFS is a real and significant health problem affecting many people who need better support and care.
This study provides epidemiological evidence for healthcare planning and resource allocation by establishing ME/CFS prevalence in England. It demonstrates that ME/CFS affects a significant proportion of the population with high unmet healthcare and social care needs, supporting the case for improved clinical recognition, service provision, and research funding. The comparison of case definitions has implications for standardizing diagnosis internationally and identifying distinct patient subgroups for targeted research.
This study does not establish the causes of ME/CFS or explain why prevalence varies geographically. It does not prove that all chronic fatigue cases are ME/CFS, nor does it identify biological mechanisms or biomarkers. The prevalence estimates represent minimums, so actual prevalence may be higher; the study's cross-sectional design cannot establish causation or long-term disease 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
Nacul, Luis C, Lacerda, Eliana M, Pheby, Derek, Campion, Peter, Molokhia, Mariam, Fayyaz, Shagufta, et al. (2011). Prevalence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in three regions of England: a repeated cross-sectional study in primary care.. BMC medicine. https://doi.org/10.1186/1741-7015-9-91
BibTeX
@article{mecfsatlas-nacul-2011-prevalence-myalgic,
author = {Nacul, Luis C and Lacerda, Eliana M and Pheby, Derek and Campion, Peter and Molokhia, Mariam and Fayyaz, Shagufta and Leite, Jose C D C and Poland, Fiona and Howe, Amanda and Drachler, Maria L},
title = {Prevalence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) in three regions of England: a repeated cross-sectional study in primary care.},
journal = {BMC medicine},
year = {2011},
doi = {10.1186/1741-7015-9-91},
note = {PubMed: 21794183},
url = {https://www.mecfsatlas.com/evidence/nacul-2011-prevalence-myalgic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/nacul-2011-prevalence-myalgic
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