Hickie, I, Lloyd, A, Hadzi-Pavlovic, D et al. · Psychological medicine · 1995 · DOI
This study examined whether all people diagnosed with ME/CFS have the same illness or whether they actually have different types. Researchers analyzed symptoms from 565 patients and found that ME/CFS is not one uniform condition—instead, they identified two distinct patient groups with different symptom patterns, illness duration, and recovery rates.
This study challenges the assumption that ME/CFS is a single disease entity and demonstrates that patients diagnosed with CFS may have different underlying biological and psychological mechanisms. Understanding these subgroups is crucial for developing targeted treatments and improving research design by ensuring participants are more homogeneous within studies.
This study does not prove that the two subgroups identified are biologically distinct entities or that they require fundamentally different treatment approaches. As a cross-sectional analysis, it cannot establish causation or determine whether subgroup membership changes over time, and the statistical clustering approach is exploratory rather than confirmatory of true disease categories.
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
Hickie, I, Lloyd, A, Hadzi-Pavlovic, D, Parker, G, Bird, K, & Wakefield, D (1995). Can the chronic fatigue syndrome be defined by distinct clinical features?. Psychological medicine. https://doi.org/10.1017/s0033291700037417
BibTeX
@article{mecfsatlas-hickie-1995-can-chronic,
author = {Hickie, I and Lloyd, A and Hadzi-Pavlovic, D and Parker, G and Bird, K and Wakefield, D},
title = {Can the chronic fatigue syndrome be defined by distinct clinical features?},
journal = {Psychological medicine},
year = {1995},
doi = {10.1017/s0033291700037417},
note = {PubMed: 8588011},
url = {https://www.mecfsatlas.com/evidence/hickie-1995-can-chronic},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/hickie-1995-can-chronic
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