Conti, F, Priori, R, De Petrillo, G et al. · Annali italiani di medicina interna : organo ufficiale della Societa italiana di medicina interna · 1994
Researchers in Rome studied 63 patients with persistent fatigue lasting at least 6 months to see how many actually had ME/CFS. They found that only 6 patients (about 10%) met the official diagnostic criteria for ME/CFS, while 37 patients (59%) had other medical conditions explaining their fatigue, such as infections or other illnesses. This suggests that ME/CFS is relatively uncommon as a cause of severe fatigue compared to other treatable conditions.
This study highlights the diagnostic challenge of ME/CFS by demonstrating that the majority of patients presenting with persistent fatigue have alternative explanable causes. For patients, it underscores the importance of thorough medical evaluation before or alongside ME/CFS diagnosis. For researchers, it provides epidemiological context for CFS prevalence in a European population and emphasizes the critical need for improved diagnostic criteria to distinguish ME/CFS from other fatigue-producing conditions.
This study does not prove that ME/CFS is rare globally—findings are specific to an Italian fatigue clinic population and may not reflect prevalence in the general population or in specialized ME/CFS centers. The cross-sectional design cannot establish causation or demonstrate how many people in the community actually have undiagnosed ME/CFS. The use of CDC criteria (which are now considered to have limitations) rather than modern case definitions affects the applicability of these findings to current diagnostic standards.
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
Conti, F, Priori, R, De Petrillo, G, Rusconi, A C, Arpino, C, & Valesini, G (1994). Prevalence of chronic fatigue syndrome in Italian patients with persistent fatigue.. Annali italiani di medicina interna : organo ufficiale della Societa italiana di medicina interna. https://pubmed.ncbi.nlm.nih.gov/7893570/
BibTeX
@article{mecfsatlas-conti-1994-prevalence-chronic,
author = {Conti, F and Priori, R and De Petrillo, G and Rusconi, A C and Arpino, C and Valesini, G},
title = {Prevalence of chronic fatigue syndrome in Italian patients with persistent fatigue.},
journal = {Annali italiani di medicina interna : organo ufficiale della Societa italiana di medicina interna},
year = {1994},
note = {PubMed: 7893570},
url = {https://www.mecfsatlas.com/evidence/conti-1994-prevalence-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/conti-1994-prevalence-chronic
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