Hemoglobin Levels and Mortality

In a UK prospective cohort of 502,188 adults followed for a median of 13.6 years, mortality was lowest at hemoglobin concentrations approximately 1–3 g/dL above the current WHO anemia thresholds, while both lower and higher concentrations were associated with increased mortality. The association between hemoglobin and all-cause mortality was U-shaped: compared with participants more than 2 g/dL below the WHO threshold, those in the lowest-risk range had substantially lower 10-year mortality (4.5% vs. 12.5%), corresponding to an adjusted hazard ratio of 2.87 for the low-hemoglobin group; even hemoglobin levels only 0–1 g/dL above the WHO threshold were associated with a modestly higher mortality risk (HR, 1.18). Similar patterns were observed for cardiovascular and cancer mortality, although associations were less consistent among women younger than 60 years and weaker at higher hemoglobin concentrations. These findings suggest that mortality risk may increase even with hemoglobin values near or below the current anemia thresholds. Source: https://www.acpjournals.org/