Analyzing the effects of anemia on the outcomes of mechanical thrombectomy in ischemic stroke patients: a systematic review and meta-analysis

Background: Anemia is a common yet often overlooked condition in patients with acute ischemic stroke (AIS) undergoing mechanical thrombectomy. Hemoglobin levels play a crucial role in oxygen transport, and their depletion may exacerbate ischemic injury and worsen functional outcomes. This meta-analysis aimed to evaluate the effect of anemia on the functional and survival outcomes of patients with AIS treated with mechanical thrombectomy. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we searched electronic databases (PubMed, Scopus, and Web of Science) to identify eligible studies reported up to January 2025. Using Review Manager software, we reported outcomes as odds ratios (ORs) or mean difference and confidence intervals (CIs). A P -value ≤ 0.05 was considered statistically significant. Results: Nine retrospective cohort studies comprising 2189 patients were included. Anemia was significantly associated with lower odds of achieving good functional outcomes (OR = 0.30, 95% CI: 0.13–0.68, P = 0.004) and a higher risk of mortality (OR = 1.76, 95% CI: 1.19–2.60, P = 0.005). No significant association was found between anemia and symptomatic intracerebral hemorrhage risk (OR = 0.95, 95% CI: 0.34–2.27, P = 0.91). Younger age, lower baseline NIH Stroke Scale, and higher hemoglobin levels were significant predictors of good prognosis. Conclusion: Anemia negatively impacted functional recovery and survival in patients with AIS undergoing mechanical thrombectomy. Given these findings, optimizing hemoglobin levels may be a potential strategy to improve patient outcomes. Further prospective studies are needed to explore the benefits of anemia correction strategies in stroke management.