Skapinakis, Petros, Lewis, Glyn, Mavreas, Venetsanos · The American journal of psychiatry · 2003 · DOI
This study looked at how different definitions of unexplained fatigue affect how many people are diagnosed and whether they also have depression or anxiety. Researchers interviewed over 5,400 primary care patients from 14 countries and found that when they required more physical symptoms in addition to fatigue, fewer people were diagnosed, but those diagnosed were more likely to also have depression or anxiety.
This research is important because it examines how different diagnostic definitions of fatigue syndromes affect both prevalence estimates and the relationship to psychiatric conditions—a key debate in ME/CFS diagnostic criteria development. Understanding whether additional somatic symptoms better distinguish unexplained fatigue from depression and anxiety has direct implications for how ME/CFS is defined internationally.
This study does not prove that psychiatric disorders cause unexplained fatigue syndromes, only that they are associated. The cross-sectional design cannot establish temporal relationships or rule out reverse causation. The study also does not address post-exertional malaise, orthostatic intolerance, or other specific ME/CFS biomarkers, making it difficult to apply these findings directly to ME/CFS definition.
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
Skapinakis, Petros, Lewis, Glyn, & Mavreas, Venetsanos (2003). Unexplained fatigue syndromes in a multinational primary care sample: specificity of definition and prevalence and distinctiveness from depression and generalized anxiety.. The American journal of psychiatry. https://doi.org/10.1176/appi.ajp.160.4.785
BibTeX
@article{mecfsatlas-skapinakis-2003-unexplained-fatigue,
author = {Skapinakis, Petros and Lewis, Glyn and Mavreas, Venetsanos},
title = {Unexplained fatigue syndromes in a multinational primary care sample: specificity of definition and prevalence and distinctiveness from depression and generalized anxiety.},
journal = {The American journal of psychiatry},
year = {2003},
doi = {10.1176/appi.ajp.160.4.785},
note = {PubMed: 12668371},
url = {https://www.mecfsatlas.com/evidence/skapinakis-2003-unexplained-fatigue},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/skapinakis-2003-unexplained-fatigue
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