Stewart, J M, Gewitz, M H, Weldon, A et al. · The Journal of pediatrics · 1999 · DOI
This study looked at how the hearts and blood pressure of adolescents with ME/CFS and a related condition called orthostatic tachycardia syndrome (OTS) respond when they stand up or are tilted upright. Researchers found that adolescents with ME/CFS had more severe problems with standing (like dizziness and fainting) than those with OTS, but the underlying patterns were quite similar. The study suggests that OTS may be a milder version of the same blood pressure and heart rate problems seen in ME/CFS.
This study provides objective physiological evidence that ME/CFS and OTS share similar mechanisms of orthostatic intolerance—a common and disabling symptom for many ME/CFS patients. Understanding the continuum between these conditions may help researchers identify the underlying biological mechanisms and lead to better diagnostic tools and treatments for managing orthostatic symptoms in ME/CFS.
This study does not prove that OTS causes CFS or vice versa, nor does it establish a causal mechanism linking them. The cross-sectional design shows correlation in physiological patterns but cannot determine whether OTS is truly a milder manifestation of the same disease or a distinct condition with overlapping features. Long-term follow-up studies would be needed to determine if patients with OTS progress to full CFS or remain stable.
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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