Systemic immune-inflammation index within the first postoperative hour as a predictor of severe postoperative complications in upper abdominal surgery: a retrospective single-center study

Abstract Background Systemic pro-inflammatory factors play a critical role in mediating severe postoperative complications (SPCs) in upper abdominal surgery (UAS). The systemic immune-inflammation index (SII) has been identified as a new inflammatory marker in many occasions. The present study aims to determine the association between SII and the occurrence of SPCs after UAS. Methods Included in this study were 310 patients with upper abdominal tumors who received UAS and subsequently were transferred to the anesthesia intensive care unit between November 2020 and November 2021 in Nanjing Drum Hospital. SPCs, including postoperative pulmonary complications (PPCs), major adverse cardiac and cardiovascular events, postoperative infections and delirium, were recorded during the hospital stay. The clinical features of the patients with and without SPCs were compared by Student’s t-test or Fisher’s exact test as appropriate. Risk factors associated with SPC occurrence were evaluated by univariable and multivariable logistic regression analyses. Receiver operating characteristic (ROC) curve analysis was used to establish a cut-off level of SII value to predict SPCs. Results Of the 310 patients receiving UAS, 103 patients (33.2%) presented at least one SPC, including PPCs (n = 62), adverse cardiovascular events (n = 22), postoperative infections (n = 51), and delirium (n = 5). Both preoperative SII and 1-h postoperative SII in patients with SPCs were significantly higher than those in patients without SPCs. Multivariate analysis showed that 1-h postoperative SII was an independent predictor for SPC occurrence (OR = 1.000, 95% CI 1.000–1.000, P = 0.007), together with postoperative C-reactive protein, postoperative arterial lactate, postoperative oxygenation-index and older age. The ROC curve showed that the optimal cutoff value of 1-h postoperative SII to predict SPCs was 754.6078 × 109/L, with an 88.3% sensitivity and a 29% specificity. Multivariate analysis also confirmed that 1-h postoperative SII > 754.6078 × 109/L was associated with increased SPC occurrence (OR = 2.656, 95% CI 1.311–5.381, P = 0.007). Conclusion Our findings demonstrated an association between the higher level of 1-h postoperative SII and SPCs, suggesting that 1-h postoperative SII, especially categorized 1-h postoperative SII using cutoff value, may be a useful tool for identifying patients at risk of developing SPCs.