Systemic Immune-Inflammation Index Predicts Poor Outcome After Elective Off-Pump CABG: A Retrospective, Single-Center Study

Abstract

To investigate the role of preoperative hematologic indices (neutrophil-lymphocyte ratio [NLR], platelet-lymphocyte ratio [PLR], systemic immune-inflammation index [SII; neutrophil × platelet/lymphocyte) in predicting short-term outcomes after off-pump coronary artery bypass grafting (OPCABG). A single-center, retrospective, risk-prediction study. A tertiary cardiac center. 1,007 patients undergoing elective OPCABG. No specific intervention. Two hundred five patients out of 1,007 (20.4%) manifested poor postoperative outcome (defined by ≥1 of: major adverse cardiac and cardiovascular events, duration of mechanical ventilation (DO-MV) >24 hours, new-onset renal failure, sepsis, and death). On univariate analysis, age, diabetes mellitus (DM), European System for Cardiac Operative Risk Evaluation II (EuroSCORE II), left-main disease, recent myocardial infarction, poor left ventricular ejection fraction, hemoglobin, NLR, PLR, and SII significantly predicted poor outcome. However, DM, EuroSCORE II, and SII emerged as independent predictors on multivariate analysis (odds ratio 0.136; 0.035-0.521, 3.377; 95% confidence interval 2.373-4.806, 1.01, 1.003-1.016). The SII cutoff of 878.06 × 103/mm3 predicted poor outcome with 97.6% sensitivity, 91%, specificity, and area under the curve 0.984. There was a significant positive correlation between the SII values and DO-MV and length of intensive care unit stay (R = 0.676; 0.527, p < 0.001). The incidence of complications, such as atrial fibrillation, intra-aortic balloon pump requirement, vasoactive-ionotropic score >20 for >6 hours, and other infections, was also significantly higher in patients with SII ≥878.06 × 103/mm3. SII constitutes a parsimonious and reproducible parameter demonstrating the potential of delineating the patients vulnerable to poor outcomes after OPCABG given the combined contribution of pro-inflammatory and pro-thrombotic corpuscular lines in computing the novel index.