Systemic Immune-Inflammation Index Predicts Major Cardiovascular Adverse Events in Patients with ST-Segment Elevated Myocardial Infarction

Abstract Background The systemic immune-inflammation index (SII) has been reported as a new prognostic marker in tumors and cardiovascular diseases Objective To investigate the association of SII with adverse cardiovascular events in patients with ST-segment elevated myocardial infarction (STEMI). Methods A retrospective observational study was conducted on 843 patients with STEMI. Patients were divided into two groups based on the median value of SII. Major adverse cardiovascular events were compared between SII groups. Cox regression analysis was used for detecting independent predictors of cardiovascular adverse events. The improvement of discrimination ability by adding SII to the traditional risk factors such as age, hypertension, diabetes mellitus, and male gender for major adverse events was calculated by c-statistics, integrated discrimination improvement, and net reclassification improvement. A two-sided p-value <0.05 was considered significant. Results High SII group was older than the low SII group (61.2±11.2, 59.2±7.9, respectively, p=0.002). The high SII group had higher rates of cardiac death, nonfatal myocardial infarction, nonfatal stroke, hospitalization for heart failure, revascularization, and composite major adverse cardiovascular events than the low SII group. SII was an independent predictor of all events mentioned above. Adding SII to traditional risk factors improved their discrimination ability for cardiovascular events. SII was superior to the neutrophil-to-lymphocyte and platelet-to- lymphocyte ratios for predicting cardiovascular adverse events. Conclusion SII was an independent predictor of major adverse events in patients with STEMI and may be used to improve the prediction of adverse events, especially when combined with traditional risk factors.