Evengård, Birgitta, Jacks, Andreas, Pedersen, Nancy L et al. · Psychological medicine · 2005 · DOI
This Swedish study contacted over 31,000 people and found that about 2.4% had symptoms matching chronic fatigue syndrome. Women were nearly four times more likely to have these symptoms than men. The researchers were surprised to find that ME/CFS may be more common than doctors previously thought.
This is one of the largest population-based epidemiological studies of ME/CFS conducted in a well-characterized cohort, providing robust prevalence estimates and revealing the striking female predominance of the illness. The findings challenge assumptions about occupational risk and suggest ME/CFS may affect a larger proportion of the population than previously recognized, with important implications for healthcare planning and research priorities.
This study does not identify causes of ME/CFS or explain why women are disproportionately affected; it only documents the association. The cross-sectional design cannot establish temporal relationships or causation. Additionally, reliance on symptom screening and medical record review may miss or misclassify cases depending on how closely the refined definition matched the true clinical entity.
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
Evengård, Birgitta, Jacks, Andreas, Pedersen, Nancy L, & Sullivan, Patrick F (2005). The epidemiology of chronic fatigue in the Swedish Twin Registry.. Psychological medicine. https://doi.org/10.1017/S0033291705005052
BibTeX
@article{mecfsatlas-evengrd-2005-epidemiology-chronic,
author = {Evengård, Birgitta and Jacks, Andreas and Pedersen, Nancy L and Sullivan, Patrick F},
title = {The epidemiology of chronic fatigue in the Swedish Twin Registry.},
journal = {Psychological medicine},
year = {2005},
doi = {10.1017/S0033291705005052},
note = {PubMed: 16168154},
url = {https://www.mecfsatlas.com/evidence/evengrd-2005-epidemiology-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/evengrd-2005-epidemiology-chronic
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