E2 ModerateModerate confidencePEM unclearCross-SectionalPeer-reviewedMachine draft
An evaluation of exclusionary medical/psychiatric conditions in the definition of chronic fatigue syndrome.
Jones, James F, Lin, Jin-Mann S, Maloney, Elizabeth M et al. · BMC medicine · 2009 · DOI
Quick Summary
This study looked at whether people diagnosed with ME/CFS who also have other medical or psychiatric conditions (like depression or thyroid disease) are actually sicker than those with ME/CFS alone. Researchers surveyed over 5,600 people in Georgia and clinically evaluated 781 of them. They found that about one-third of people had additional conditions, but surprisingly, people with and without these extra conditions reported similar levels of fatigue and disability.
Why It Matters
This research challenges the assumption that excluding people with comorbid conditions from CFS studies produces a 'purer' population—it suggests that comorbid conditions may not substantially change how sick someone is. Understanding whether exclusionary criteria actually improve research validity has important implications for how future ME/CFS studies define their participants and interpret results.
Observed Findings
- 29% of telephone survey respondents (1,609/5,623) reported exclusionary diagnoses; this increased to 36% upon clinical evaluation.
- Subjects with and without exclusionary conditions reported similar levels of fatigue (MFI) and functional impairment (SF-36).
- Exclusionary conditions were more common in women, Black participants, and rural residents.
- Subjects with CFS-like illness (not meeting formal definition) were more likely to have an exclusionary diagnosis.
- After adjusting for demographics, BMI, and symptom measures, CFS-like illness did not remain significantly associated with exclusionary diagnoses.
Inferred Conclusions
- Medical and psychiatric illnesses are common among people with fatigue-like illness and should not automatically exclude patients from diagnosis or treatment consideration.
- People with exclusionary conditions experience similar disability to those without, suggesting exclusionary criteria may not improve sample homogeneity in terms of illness severity.
- Clinical evaluation of potentially treatable comorbid conditions is important for all unwell patients, regardless of CFS diagnosis.
Remaining Questions
- Does the presence of exclusionary conditions affect response to specific ME/CFS treatments?
What This Study Does Not Prove
This study does not prove that exclusionary conditions are unimportant for ME/CFS diagnosis or management. The cross-sectional design cannot establish causation or temporal relationships. Additionally, the study uses self-reported diagnoses and telephone screening rather than standardized biological measures, so the true prevalence and impact of comorbidities may differ.
Tags
Symptom:Fatigue
Method Flag:PEM Not DefinedWeak Case DefinitionMixed Cohort
Metadata
- DOI
- 10.1186/1741-7015-7-57
- PMID
- 19818157
- Review status
- Machine draft
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 8 April 2026
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 →
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