Predictors of Acute Kidney Injury in Older Adults With Extracapsular Hip Fractures

Objective: Postoperative acute kidney injury (AKI) is a common and serious complication following hip fracture surgery in older adults. This study aimed to identify predictors of postoperative AKI and evaluate its association with short-term complications after extracapsular hip fracture surgery. Methods: A retrospective cohort study was conducted using TriNetX Analytics, a federated electronic health record network of 109 United States healthcare organizations (2015-2025). Adults aged ≥ 65 years undergoing extracapsular hip fracture surgery (CPT 27244/27245) were included; those with prior AKI (ICD-10-CM N17) were excluded. Propensity score matching was performed 1:1. Predictors were assessed using Cox proportional hazards modeling and postoperative complications were compared using risk ratios, odds ratios, and Kaplan-Meier survival analysis. Results: Among 46,287 eligible patients, 1,413 matched pairs (n=2,826) were analyzed. Predictors of postoperative AKI included Black race (HR=1.64), White race (HR=1.21), elevated preoperative serum chloride (HR=1.04), bicarbonate (HR=1.03), creatinine (HR=1.18), and decreased serum protein (HR=1.11). Protective factors included Hispanic/Latino ethnicity (HR=0.70), preoperative opioid use (HR=0.58), elevated serum sodium (HR=0.97), and Tdap vaccination (HR=0.82). Postoperative AKI was associated with increased 30-day risk of myocardial infarction (RR=8.01), sepsis (RR=5.99), respiratory failure (RR=5.30), arrhythmia (RR=2.22), deep vein thrombosis (RR=1.98), transfusion (RR=1.92), and mortality (RR=2.22). Conclusions: Postoperative AKI was independently associated with increased short-term morbidity and mortality following extracapsular hip fracture surgery in older adults. Recognition of perioperative risk factors may support earlier identification and targeted strategies to reduce AKI incidence and improve postoperative outcomes.