Anemia impacts short-term and long-term mortality risk after acute ischemic stroke

BACKGROUND: The relationship between hemoglobin concentration and all-cause mortality in acute ischemic stroke (AIS) patients remains unclear due to conflicting findings. This study aims to evaluate the impact of hemoglobin concentration on the risk of both short-term and long-term all-cause mortality in AIS patients from a nationwide stroke registry.

METHOD: We utilized data from the Singapore Stroke Registry (SSR), including patients >18years old at first AIS onset, and received treatment at a local hospital between 2005 and 2020. Patients were stratified according to sex-specific hemoglobin concentration cut-offs on anemia severity and polycythemia from the World Health Organization. Multivariate logistic regression and Cox proportional hazards modeling were performed, adjusting for demographics and cardiovascular risk factors.

RESULTS: A total of 56,884 ischemic stroke patients were included, of which 66.8% had no anemia, 15.7% had mild anemia, 12.2% had severe anemia, and 5.3% had polycythemia. The cohort was predominantly male (57%), with a median age of 68 years. The median follow-up duration was 10-years (IQR 7-13). Compared to patients with normal-range hemoglobin, both mild and severe anemia was associated with elevated short-term and long-term risks of all-cause mortality. Severe anemia was associated with the highest risk of all-cause mortality, with hazard ratios of 1.99 (95%CI:1.92-2.06) at 30-days, 1.73 (95%CI:1.66-1.81) at 1-year, and 1.52 (95%CI:1.41-1.64) at 5-years. However, the excess risk associated with severe anemia appeared to attenuate at 10-years, whilst the elevated risk persisted among patients with mild anemia.

CONCLUSION: In this nationwide stroke registry, anemia is prevalent among AIS patients and is significantly associated with both short-term and long-term mortality.