Association of SIRI and NLPR with post-operative pneumonia in middle-aged and elderly patients after hip fracture surgery.

Authors

Yan Tan, Fang Chai

Published in

Frontiers in medicine. Volume 13. Pages 1861666. Epub Jul 01, 2026.

Abstract

Post-operative pneumonia (POP) is one of the most common complications following hip fracture surgery. The Systemic Inflammation Response Index (SIRI) and the Neutrophil-to-Lymphocyte-to-Platelet Ratio (NLPR) are novel inflammatory markers derived from peripheral blood cell counts. This study aims to evaluate the association of SIRI and NLPR at admission with hospital-acquired post-operative pneumonia in middle-aged and elderly patients after hip fracture surgery.
A retrospective study was conducted with 452 patients aged 45 years or older who underwent hip fracture surgery. The Systemic Inflammation Response Index (SIRI) and the Neutrophil-to-Lymphocyte-to-Platelet Ratio (NLPR) were calculated based on peripheral blood cell counts (including neutrophil, monocyte, lymphocyte, and platelet counts) measured at admission. According to the occurrence of hospital-acquired post-operative pneumonia, patients were divided into a pneumonia group (n = 25) and a non-pneumonia group (n = 427). Multivariable logistic regression analysis was employed to evaluate the association of SIRI and NLPR with hospital-acquired post-operative pneumonia after hip fracture. Receiver operating characteristic (ROC) curve analysis was used to assess the performance of SIRI and NLPR for post-operative pneumonia and to determine the optimal cut-off values for each indicator. Additionally, restricted cubic spline analysis adjusted for covariates and subgroup analysis were performed.
A total of 452 patients were included in this study, of whom 25 (5.53%) developed post-operative pneumonia. Both SIRI and NLPR showed a positive association with the risk of pneumonia after hip fracture surgery. Both SIRI and NLPR showed moderate discriminative performance (AUC: 0.701 and 0.738, respectively). The difference between the two AUCs was not statistically significant (DeLong test, P = 0.247). An elevated NLPR above the optimal cut-off value of 2.879 was significantly associated with an increased incidence of POP (OR = 5.47, 95% CI: 1.95-20.8). Furthermore, additional restricted cubic spline and subgroup analyses supported the robustness of this finding.
Both SIRI and NLPR are associated with the occurrence of hospital-acquired post-operative pneumonia in middle-aged and elderly patients with hip fracture. Both markers demonstrated moderate discriminative ability, with high negative predictive values, suggesting they may be useful as auxiliary screening tools for ruling out POP in low-risk patients. The numerically higher AUC of NLPR did not reach statistical significance compared with SIRI. However, given the low positive predictive value, it is more suitable for ruling out low-risk patients rather than definitively identifying those who will develop post-operative pneumonia. Its clinical utility as an early warning indicator requires further external validation.

PMID:
42460070
Bibliographic data and abstract were imported from PubMed on 16 Jul 2026.

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