Association Between Blood Hemoglobin Concentration and Mortality by Age and Sex : A Prospective Cohort Study

The authors aimed to investigate the relationship between baseline blood hemoglobin concentration and long-term mortality, stratified by age and sex, in a large UK cohort. They found a U-shaped association, indicating that mortality risk was lowest at hemoglobin levels 1 to 3 g/dL above the WHO thresholds, with increased mortality observed both below and above this range. These findings suggest that while current WHO thresholds may not need revision, they could inform clinical assessments of hemoglobin levels.