Friedberg, Fred, Tintle, Nathan, Clark, Jake et al. · Fatigue : biomedicine, health & behavior · 2015 · DOI
This study compared how common prolonged, disabling fatigue is in Ukraine versus the United States by surveying thousands of people in both countries. Researchers found that prolonged fatigue was more common in Ukraine (5.2%) than in the U.S. (3.7%), and identified different risk factors in each country—such as socioeconomic status, mood disorders, and various health conditions. Importantly, about one-fifth of people with prolonged fatigue had no other diagnosed medical or mental health condition.
This study provides international epidemiological data on prolonged fatigue prevalence and identifies that a significant proportion of people with disabling fatigue have no other recognized medical or psychiatric diagnosis—suggesting fatigue can be a primary condition worthy of clinical attention. Understanding varied risk factors across populations helps researchers identify whether fatigue pathophysiology differs by geography or whether environmental and socioeconomic factors modulate disease presentation and recognition.
This study does not prove that any identified risk factor *causes* prolonged fatigue—it only shows associations. The cross-sectional design cannot establish temporal relationships between risk factors and fatigue onset. Additionally, the study uses neurasthenia (ICD-10) rather than ME/CFS diagnostic criteria, so findings may not directly apply to ME/CFS specifically.
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 →
Spotted an error in this entry? Report it →