ObjectiveTo determine the predictive value of preoperative systemic immune-inflammatory index (SII) regarding the development of postoperative pulmonary complications (PPCs) after abdominal surgery.MethodsThisretrospective study involved 433 patients undergoing elective abdominal surgery. Logistic regression risk model was used to evaluate the prognostic value of SII. We drew the receiver-operating characteristic (ROC) curve and calculated the area under the ROC curve to compared the predictive ability of SII, platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and monocyte-to- lymphocyte ratio (MLR).ResultsThe independent risk factors of PPCs were preoperative respiratory diseases, preoperative history of chronic liver disease, maintenance of intravenous or inhalation anesthesia, and intraoperative infusion of more colloid (P<0.05). However, SII, PLR, NLR, and MLR did not predict the occurrence of PPCs, and they also did not predict ≥3 grade of PPCs (AUC<0.60, P>0.05).ConclusionsPreoperative SII is not a prognostic biomarker of PPCs occurrence in patients undergoing elective abdominal surgery. Other biomarkers, such as PLR, NLR, and MLR, also have no predictive value for the PPCs in these patients.