Systemic immune-inflammation index associated with contrast-induced nephropathy after elective percutaneous coronary intervention in a case-control study

Elevated systemic immune-inflammation index (SII) has associated with coronary heart disease and poor clinical outcomes. However, the relationship between SII and contrast-induced nephropathy (CIN) in patients who underwent elective percutaneous coronary intervention (PCI) is still unclear. We aimed to investigate the association of SII with the development of CIN in elective PCI patients. A retrospective study with 241 participants was performed from March 2018 to July 2020. CIN was defined as any of the following: increase in serum creatinine (SCr) level by ≥0.5 mg/dl (≥44.2 mol/L) or increase in SCr to ≥25% over the baseline value within 48–72 h after PCI. The SII levels in patients with CIN (n = 40) were significantly higher than those without. In correlation analysis, SII positively correlated to uric acid but negatively with the estimated glomerular filtration rate. Increased log2(SII) levels were independent risk factors for patients with CIN [odds ratio (OR) = 2.686; 95% confidence interval (CI), 1.457–4.953]. In the subgroup analysis, increased log2(SII) was strongly associated with the presence of CIN in male participants (OR = 3.669; 95% CI, 1.925–6.992; P < 0.05), whereas no association was found in females (OR = 1.552; 95% CI, 0.533–4.515; P > 0.05). Receiver operating characteristic analysis demonstrated that in a cutoff of 586.19, SII showed 75% sensitivity and 54.2% specificity for predicting CIN in patients undergoing elective PCI, respectively. In conclusion, elevated SII was an independent risk factor of CIN development in patients undergoing elective PCI, particularly in male people.