Association between Systemic Immune-Inflammation Index and Systemic Inflammation Response Index and Outcomes of Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Systemic immune-inflammation index (SII) and systemic inflammation response index (SIRS) are being increasingly used to predict outcomes of various diseases. However, its utility for acute ischemic stroke (AIS) has not been established. Through this first systematic review and meta-analysis, we aimed to collate data on the prognostic ability of SII and SIRI for predicting functional outcomes and mortality after AIS. PubMed, CENTRAL, Scopus, Embase, and Web of Science were searched up to January 5, 2023, for studies reporting the association between SII or SIRI and outcomes of AIS. Adjusted data were pooled in a random-effects model. Meta-regression was conducted for variable cut-offs. Twelve studies were included. Pooled analysis of data showed that high SII was associated with poor functional outcomes after AIS (OR: 2.35 95% CI: 1.77, 3.10 I(2) = 44% P < 0.00001). Meta-regression showed an increasing effect size with a higher cut-off of SII. Similarly, the meta-analysis demonstrated that AIS patients with high SIRI were at an increased risk of poor functional outcomes (OR: 1.69 95% CI: 1.08, 2.65 I(2) = 78% P = 0.02). No association was noted with different cut-offs on meta-regression. Data on mortality were scarce but were suggestive of a higher risk of mortality with high SII and SIRI. SII and SIRI can be used to predict poor functional outcomes in AIS patients. Data on mortality are scarce to derive strong conclusions. Limited number of studies and variable cut-offs are important limitations that need to be overcome by future studies.