Venous Blood Cell Ratios as Predictors of Reperfusion Outcomes in Ischemic Stroke: A Systematic Review and...

Inflammation plays a critical role in the pathophysiology of acute ischemic stroke (AIS). Ratios derived from routine blood counts, especially the neutrophil-to-lymphocyte ratio (NLR), have been proposed as prognostic biomarkers, but their value in patients receiving reperfusion therapies-intravenous thrombolysis (IVT) or mechanical thrombectomy (MT)-remains uncertain.

We systematically searched PubMed, Cochrane Library, Web of Science, and Scopus on November 30, 2024, following PRISMA guidelines. Eligible studies included patients with AIS treated with IVT or MT that reported associations between pre-treatment blood cell ratios and outcomes measured by the modified Rankin Scale (mRS). Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random-effects models.

Fifty-seven studies with 17,394 patients were included. NLR was the predominantly studied biomarker. In the MT subgroup, elevated NLR predicted poor 3-month outcome (OR 1.09, 95% CI 1.04-1.15) and higher mortality (OR 1.05, 95% CI 1.01-1.08). In IVT-treated patients, higher NLR also predicted poor outcome (OR 1.11, 95% CI 1.01-1.21) with lower heterogeneity across studies. Other ratios showed variable associations: lymphocyte-to-monocyte ratio (LMR) appeared protective, while platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-neutrophil ratio (PNR) showed inconsistent or null results. Data regarding hemorrhagic transformation were heterogeneous and unsuitable for meta-analysis.

Elevated pre-treatment NLR consistently predicted poor outcome and mortality after reperfusion therapy for AIS, supporting its role as a simple biomarker for early risk stratification. Future large, prospective multicenter studies with standardized methods are needed to confirm the clinical utility of these inflammatory ratios in stroke management.