Prognostic nutritional index with postoperative complications and 2-year mortality in hip fracture patients: an observational cohort study

Background: The prognostic nutritional index (PNI) has been proposed as a useful prognostic tool in multiple populations. However, its prognostic value has not been fully evaluated in the hip fracture population. We aimed to assess the relationship between PNI and postoperative complications as well as 2-year all-cause mortality in the hip fracture population. Materials and methods: We included patients aged 45 or older who underwent surgery for hip fracture between 2000 and 2022. The baseline serum albumin and total lymphocyte count were used to calculate PNI with the following formula: 10 × serum albumin level (g/dL) + 0.005 × total lymphocyte count (per mm 3 ). Patients were classified into low, medium, and high categories based on tertiles of PNI (≤ 43.23, 43.23-47.35, and > 47.35, respectively). Logistic regression and Cox proportional hazards models were used to calculate the odds ratio (OR) for postoperative compilations and the hazard ratio (HR) for mortality, adjusting for potential confounders. Results: Of 3,351 hip patients, 236 (7.04%) developed postoperative complications, and 305 (9.10%) died during the 2-year follow-up. Compared to the low-category patients, the medium- and high-category patients showed lower odds of postoperative complications (ORs 0.69, 95% CI, 0.48-0.98; and 0.61, 95% CI, 0.40-0.93, respectively), and lower hazard of 2-year mortality (HRs 0.66, 95% CI 0.49-0.88; and 0.61, 95% CI 0.42-0.88, respectively). These associations were robust across a series of analyses, including subgroup analyses and dose-response sensitivity analyses. Conclusion: PNI is an independent predictor of postoperative complications and 2-year all-cause mortality in hip fracture patients. PNI can be used to identify patients who may be at high risk of a poor prognosis.