Elevated neutrophil percentage-to-albumin ratio is associated with postoperative pneumonia in patients with hip fractures.

Background: Hip fractures (HF) are common in older adults and are frequently complicated by postoperative pneumonia (POP), which markedly worsens clinical outcomes and increases healthcare burden. Early identification of patients at high risk of POP using simple and readily available indices may facilitate targeted preventive strategies. This study aimed to evaluate the associations between common inflammatory and nutritional indices and the risk of POP in patients with HF. Methods: Clinical data from patients hospitalized with HF at the Fourth Affiliated Hospital of Anhui Medical University between May 2016 and November 2022 and between March 2023 and May 2025 were retrospectively analyzed. For each composite index, three logistic regression models with progressive adjustment for confounders were constructed to assess associations with POP. Restricted cubic spline (RCS) analyses were applied to indices with significant associations to explore dose-response relationships. Predictive performance was evaluated using receiver operating characteristic (ROC) curves. Model calibration was assessed using the Hosmer-Lemeshow goodness-of-fit test. Subgroup analysis was conducted to examine the stability of the most effective predictive index across different subgroups. Results: A total of 1,249 patients with HF were included, of whom 122 (9.8%) developed POP. Among ten evaluated indices, the neutrophil percentage-to-albumin ratio (NPAR) showed the strongest predictive performance. The Hosmer-Lemeshow goodness-of-fit test was used to assess model fit, and the results indicated that the model fit well (χ Conclusion: NPAR is an independent risk factor for postoperative pneumonia in older patients with hip fractures and demonstrates potential value for early risk stratification.