Meeus, Mira, Ickmans, Kelly, Struyf, Filip et al. · Clinical rheumatology · 2016 · DOI
This study compared people with ME/CFS to people with multiple sclerosis and healthy volunteers to see how sick they were and how well they could function. Researchers found that people with ME/CFS had worse physical abilities (like muscle strength and recovery), more severe symptoms, lower quality of life, and more difficulty with daily activities. They also discovered that when ME/CFS patients also had fibromyalgia (widespread pain), their overall symptom burden was much greater.
This research helps clarify how different diagnostic criteria for ME/CFS compare and shows that fibromyalgia as a co-diagnosis identifies a substantially sicker patient subgroup. Understanding these distinctions is important for clinicians making accurate diagnoses, for patients understanding their condition, and for researchers designing future treatment studies.
This study does not establish causation or mechanisms—it only documents that certain symptom patterns and functional impairments exist in ME/CFS. The study's relatively small sample size and cross-sectional design limit generalizability. It also does not prove that ME or Canadian criteria are superior to CDC criteria, only that they do not identify a clinically distinct group in this sample.
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
Meeus, Mira, Ickmans, Kelly, Struyf, Filip, Kos, Daphne, Lambrecht, Luc, Willekens, Barbara, et al. (2016). What is in a name? Comparing diagnostic criteria for chronic fatigue syndrome with or without fibromyalgia.. Clinical rheumatology. https://doi.org/10.1007/s10067-014-2793-x
BibTeX
@article{mecfsatlas-meeus-2016-what-name,
author = {Meeus, Mira and Ickmans, Kelly and Struyf, Filip and Kos, Daphne and Lambrecht, Luc and Willekens, Barbara and Cras, Patrick and Nijs, Jo},
title = {What is in a name? Comparing diagnostic criteria for chronic fatigue syndrome with or without fibromyalgia.},
journal = {Clinical rheumatology},
year = {2016},
doi = {10.1007/s10067-014-2793-x},
note = {PubMed: 25308475},
url = {https://www.mecfsatlas.com/evidence/meeus-2016-what-name},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/meeus-2016-what-name
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