Unger, Elizabeth R, Lin, Jin-Mann S, Chen, Yang et al. · Journal of clinical medicine · 2024 · DOI
Researchers studied 465 ME/CFS patients across seven specialized clinics in the United States to see if doctors diagnosed and recognized the same disease. They found that while the clinics had similar patients, there was tremendous variation in how sick individual patients were—some had mild symptoms while others were severely affected. This suggests that ME/CFS may naturally come in many different forms, and understanding these differences could help improve research and treatment.
This study provides evidence that ME/CFS is a real, recognizable condition across different specialty clinics, validating patient experiences and clinical expertise. Understanding that ME/CFS naturally varies widely among patients is crucial for designing better research studies and developing treatments that work for different patient subgroups, rather than treating all ME/CFS as identical.
This study does not identify the causes of ME/CFS heterogeneity or explain why patients vary so widely in their symptoms and severity. It does not test treatments or determine whether different symptom patterns represent distinct biological subtypes versus a single disease with variable manifestation. The cross-sectional design cannot establish how heterogeneity changes over time within individual patients.
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
Unger, Elizabeth R, Lin, Jin-Mann S, Chen, Yang, Cornelius, Monica E, Helton, Britany, Issa, Anindita N, et al. (2024). Heterogeneity in Measures of Illness among Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Is Not Explained by Clinical Practice: A Study in Seven U.S. Specialty Clinics.. Journal of clinical medicine. https://doi.org/10.3390/jcm13051369
BibTeX
@article{mecfsatlas-unger-2024-heterogeneity-measures,
author = {Unger, Elizabeth R and Lin, Jin-Mann S and Chen, Yang and Cornelius, Monica E and Helton, Britany and Issa, Anindita N and Bertolli, Jeanne and Klimas, Nancy G and Balbin, Elizabeth G and Bateman, Lucinda and Lapp, Charles W and Springs, Wendy and Podell, Richard N and Fitzpatrick, Trisha and Peterson, Daniel L and Gottschalk, C Gunnar and Natelson, Benjamin H and Blate, Michelle and Kogelnik, Andreas M and Phan, Catrina C and On Behalf Of The McAm Study Group},
title = {Heterogeneity in Measures of Illness among Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Is Not Explained by Clinical Practice: A Study in Seven U.S. Specialty Clinics.},
journal = {Journal of clinical medicine},
year = {2024},
doi = {10.3390/jcm13051369},
note = {PubMed: 38592199},
url = {https://www.mecfsatlas.com/evidence/unger-2024-heterogeneity-measures},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/unger-2024-heterogeneity-measures
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