E2 ModerateModerate confidencePEM unclearCross-SectionalPeer-reviewedMachine draft
Comorbidity of postural orthostatic tachycardia syndrome and chronic fatigue syndrome in an Australian cohort.
Reynolds, G K, Lewis, D P, Richardson, A M et al. · Journal of internal medicine · 2014 · DOI
Quick Summary
This study looked at patients with ME/CFS to see how many also have POTS (a condition where heart rate increases too much when standing). The researchers found that about 1 in 9 ME/CFS patients also had POTS, and these patients were younger, got sick more recently, and found it much harder to stand for long periods compared to ME/CFS patients without POTS.
Why It Matters
Many ME/CFS patients experience POTS-like symptoms, and identifying this as a common comorbidity (affecting ~11% in this cohort) helps clinicians recognize and screen for it. Understanding that CFS-POTS patients form a distinct subgroup with different haemodynamic characteristics may lead to more targeted, personalized treatment approaches and better recognition of which patients may benefit from POTS-specific interventions.
Observed Findings
- 11% (33/306) of ME/CFS clinic patients met diagnostic criteria for comorbid POTS.
- CFS-POTS patients were significantly younger and had shorter illness duration than CFS-only patients.
- CFS-POTS patients experienced lower baseline diastolic blood pressure and higher heart rates during standing tasks.
- CFS-POTS patients stood for significantly shorter periods and reported greater task difficulty.
- Heart rate variability was a significant predictor of perceived fatigue difficulty across the entire ME/CFS cohort.
Inferred Conclusions
- CFS-POTS represents a distinct pathophysiological subgroup within the ME/CFS population with specific haemodynamic abnormalities.
- Clinicians should prioritize screening younger ME/CFS patients for comorbid POTS.
- Heart rate variability measures may serve as an objective marker of fatigue severity in ME/CFS patients.
Remaining Questions
- Does POTS contribute to worse long-term outcomes in ME/CFS, or do both conditions share a common underlying mechanism?
- Are there effective treatments specifically targeting the CFS-POTS subgroup, and do they differ from CFS-only treatment approaches?
What This Study Does Not Prove
This study does not prove that POTS causes ME/CFS or vice versa—only that they frequently occur together. The cross-sectional design means we cannot determine whether autonomic dysfunction leads to fatigue or whether chronic fatigue itself produces autonomic changes. Results are limited to this Australian clinic population and may not generalize to all ME/CFS patients globally.
Tags
Symptom:Orthostatic IntoleranceFatigue
Biomarker:Blood Biomarker
Method Flag:Weak Case DefinitionExploratory OnlyStrong Phenotyping
Metadata
- DOI
- 10.1111/joim.12161
- PMID
- 24206536
- 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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