Abstract Background Systemic inflammatory markers have emerged as potential predictors of cerebrovascular and cardiovascular events. The Systemic Immune-Inflammation Index (SII), calculated from platelet, neutrophil, and lymphocyte counts, has been proposed as a novel biomarker for vascular inflammation and thrombotic risk. However, its association with stroke prevalence remains uncertain. Purpose This meta-analysis aimed to systematically evaluate the association between the Systemic Immune-Inflammation Index (SII) and stroke prevalence by synthesising evidence from recent studies. By pooling data from multiple sources, we sought to determine whether elevated SII levels are linked to an increased risk of stroke, particularly in individuals with cardiovascular comorbidities. This analysis provides insights into the potential role of SII as a biomarker for stroke risk stratification in clinical practice. Methods We performed a systematic review and meta-analysis, searching PubMed, Embase, and Cochrane databases to identify studies assessing SII levels in adults with and without a previous history of stroke. We followed PRISMA reporting guidelines. Eligible studies were analysed using a random-effects model, pooled as hazard ratio (HR) and odds ratio (OR). Heterogeneity was assessed using the I² statistic. We used Review Manager 4.1 for statistical analysis. Results A total of nine observational studies with 151,042 patients were included. The average age was 57.57 years, and the male population percentage was 49.2%. The meta-analysis demonstrated that higher SII levels were significantly associated with increased stroke prevalence, with all the values adjusted for potential confounders (HR 1.30; 95% CI 1.22–1.37; p 0.00001; I² = 60%). A subgroup analysis of hypertensive patients with high SII levels showed an increased risk of stroke (OR 1.06; 95% CI 1.04–1.08; p 0.00001; I² = 99%). Conclusion Elevated SII levels are strongly associated with increased stroke prevalence, especially in high-risk cardiovascular populations. Given its ease of calculation from routine blood tests, SII could serve as a valuable biomarker for stroke risk stratification in cardiology and neurology settings. However, the high heterogeneity between studies indicates significant variability in the results, suggesting the need for additional analyses to better understand this association.SII in Stroke SII in hypertension patients
Assis et al. (Sat,) studied this question.