Arpino, C, Carrieri, M P, Valesini, G et al. · Annali dell'Istituto superiore di sanita · 1999
This study compared how many patients were diagnosed with ME/CFS using two different diagnostic definitions from 1988 and 1994. The researchers found that the 1994 definition diagnosed more patients as having CFS, but these additional patients were less likely to have had a sudden onset of illness or signs suggesting an infectious trigger like fever or sore throat. This suggests the two definitions captured somewhat different groups of people.
ME/CFS diagnostic criteria have evolved over time, and understanding how these different definitions capture different patient populations is crucial for comparing research studies, ensuring consistent diagnosis in clinical settings, and recognizing that patients with similar fatigue may have different underlying disease presentations. This work highlights that case definition choice significantly affects who gets diagnosed, which has implications for research recruitment and clinical recognition of the condition.
This study does not prove that either the 1988 or 1994 definition is superior or more accurate. It is purely descriptive and cannot establish whether the differences in symptom profiles reflect true biological differences between groups or simply artifacts of how each definition's criteria are structured. The study was conducted in 1999 and does not address how these older definitions compare to current diagnostic criteria.
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
Arpino, C, Carrieri, M P, Valesini, G, Pizzigallo, E, Rovere, P, Tirelli, U, et al. (1999). Idiopathic chronic fatigue and chronic fatigue syndrome: a comparison of two case-definitions.. Annali dell'Istituto superiore di sanita. https://pubmed.ncbi.nlm.nih.gov/10721210/
BibTeX
@article{mecfsatlas-arpino-1999-idiopathic-chronic,
author = {Arpino, C and Carrieri, M P and Valesini, G and Pizzigallo, E and Rovere, P and Tirelli, U and Conti, F and Dialmi, P and Barberio, A and Rusconi, N and Bosco, O and Lazzarin, A and Saracco, A and Moro, M L and Vlahov, D},
title = {Idiopathic chronic fatigue and chronic fatigue syndrome: a comparison of two case-definitions.},
journal = {Annali dell'Istituto superiore di sanita},
year = {1999},
note = {PubMed: 10721210},
url = {https://www.mecfsatlas.com/evidence/arpino-1999-idiopathic-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/arpino-1999-idiopathic-chronic
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