Association Between Systemic Immune-Inflammation Index and Adverse Outcomes in Patients With Acute Coronary Syndrome: A Meta-Analysis

The systemic immune-inflammation index (SII) has been developed for the risk prognostication of acute coronary syndrome (ACS) patients. This meta-analysis aimed to assess the value of SII for predicting adverse outcomes in ACS patients. Relevant studies were identified by searching the PubMed, Web of Science, and Embase databases. Studies that investigated the association of SII with all-cause mortality or major adverse cardiovascular events (MACEs) in ACS patients were eligible. The short-term outcomes were defined as adverse events occurring during the hospital and within 30 days. 11 studies with 16,596 patients were eligible for analysis. A random effect meta-analysis indicated that a higher SII level significantly predicted short-term death (hazard ratios [HR] 2.60; 95% confidence intervals [CI] 1.29-5.25) and long-term all-cause mortality (HR 2.40; 95% CI 1.25-4.59), even after adjusting for traditional confounding factors. Additionally, a higher SII level was also significantly associated with an increased risk of short-term MACEs (HR 1.61; 95% CI 1.28-2.03) and long-term MACEs (HR 2.43; 95% CI 1.74-3.40). These findings suggest that SII level has a strong prognostic value for both MACEs and all-cause mortality in patients with ACS. Determining the SII level has the potential to improve risk prognostication in ACS patients.