Relationship between preoperative neutrophil to high-density lipoprotein ratio and postoperative systemic inflammatory response syndrome in elderly patients: a retrospective cohort study.

Background: Systemic inflammatory response syndrome (SIRS) remains a serious health problem that consumes a large amount of medical resources. The objective of the study was to investigate whether older patients with a high neutrophil to high-density lipoprotein ratio (NHR) before surgery were more susceptible to postoperative SIRS.

Methods: This retrospective cohort study was conducted on patients older than 65 years admitted to the two campuses of the Third Affiliated Hospital of Sun Yat-sen University between January 2015 and September 2020. Patient baseline characteristics such as demographic information, medical history, laboratory test results, and variables related to postoperative SIRS were obtained from the electronic health record system. The main outcome was the occurrence of postoperative SIRS during the initial three days after surgery. The main exposure was the NHR, divided into two groups according to the optimal receiver operating characteristic (ROC) cut-off value: NHR < 4.82 and NHR ≥ 4.82.

Results: The study involved 5696 older patients, among whom 1419 (24.91%) developed SIRS. The ROC analysis showed that the NHR had the largest curve area for predicting postoperative SIRS. The NHR ≥ 4.82 was independently linked to a higher risk of postoperative SIRS (aOR = 1.29, 95% CI: 1.10-1.52, P = 0.002). This association remained robust in various sensitivity and subgroup analyses. The NHR ≥ 4.82 was correlated with an elevated risk of hospital mortality, prolonged postoperative hospital stays, and increased direct medical expenses.

Conclusions: The study found that older patients undergoing general anesthesia with NHR ≥ 4.82 were associated with an increased risk of postoperative SIRS.