Neutrophil-Lymphocyte Ratio Trajectories Predict Mortality and Medical Complications in Hip Fracture Patients Undergoing Hemiarthroplasty.

Abstract

Hip fractures are associated with high rates of mortality and medical complications. The neutrophil-lymphocyte ratio (NLR) is an inflammatory biomarker gaining recognition as a prognostic indicator. Here we sought to identify a high-risk patient population with a pathologic postoperative inflammatory response using NLR trajectories. Patients ≥ 55 years old who underwent hemiarthroplasty for intracapsular proximal femur fracture were identified using a large national database from 2016 to 2023. Latent profile analysis was conducted to classify four distinct NLR trajectories from preoperative day one to postoperative day two. Mixed effect multivariable models were conducted to evaluate the adjusted odds ratio (aOR) of the NLR class on mortality and medical complications. There were 9,282 patients designated "Blunted Phenotype," "Resolving Phenotype," "Delayed Phenotype," and "Non-resolving Phenotype," representing 73.6, 19.2, 5.4, and 1.8% of the cohort, respectively. In the adjusted analyses, each class carried higher rates and odds of mortality compared with blunted phenotypes (1.8%): resolving phenotypes (3.4%) (aOR = 1.5, 95% confidence interval (CI) = 1.1 to 2.0), delayed phenotypes (6.0%) (aOR = 2.3, 95% CI = 1.5 to 3.6), and non-resolving phenotypes (15.3%) (aOR = 5.4, 95% CI = 2.2 to 8.9). Similarly, unique NLR trajectories were associated with medical complications when compared to blunted phenotypes (36.1%): resolving phenotypes (45.7%) (aOR = 1.2, 95% CI = 1.1 to 1.4), delayed phenotypes (56.4%) (aOR = 1.7, 95% CI = 1.4 to 2.0), and non-resolving phenotypes (67.1%) (aOR = 2.2, 95% CI = 1.5 to 3.1). The NLR trajectories following hip fracture surgery are predictive of mortality. Patients who have incomplete or failed resolution of early inflammation experience significantly higher rates of mortality and medical complications.