Association of Eosinophil Counts and Ratios With Clinical Outcomes After Acute Ischemic Stroke

BACKGROUND: Evidence links eosinopenia to poor 3-month outcomes after stroke, but its long-term prognostic value in acute ischemic cerebrovascular events remains unclear. This study aimed to evaluate the association between eosinophil counts (and ratios) and 5-year clinical outcomes in patients with acute ischemic stroke or transient ischemic attack (TIA). METHODS: We analyzed data from the Third China National Stroke Registry (CNSR-III). Patients with acute ischemic stroke or TIA were categorized into quartiles based on eosinophil counts and ratios measured within 24 h of admission. Using the highest quartile as the reference, we calculated hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs) for adverse outcomes. The association of eosinophil levels with 5-year risks of stroke recurrence, poor functional outcome, all-cause death, and composite vascular events was evaluated. RESULTS: A total of 12,745 participants were enrolled. Compared to the fourth quartile of eosinophil counts, the first quartile were associated with an increased risk of stroke recurrence (adjusted hazard ratio [HR] = 1.25, 95% confidence interval [CI]: 1.10-1.41) and ischemic stroke recurrence (adjusted HR, 1.25; 95% CI: 1.10-1.42). Similar associations were observed over 5 years for poor functional outcome (adjusted odds ratio [OR] = 1.57, 95% CI: 1.40-1.76), composite vascular events (adjusted HR = 1.15, 95% CI: 1.02-1.29), and all-cause death (adjusted HR = 1.53, 95% CI: 1.32-1.77). Parallel results were found for eosinophil ratios. CONCLUSIONS: This study demonstrated that low levels of both eosinophil counts and eosinophil ratios were associated with an increased risk of adverse clinical outcomes at 5 years of follow-up in patients with ischemic stroke or TIA.