The preoperative BUN-to-albumin ratio predicts early mortality after geriatric intertrochanteric fracture surgery: a retrospective cohort study

Early postoperative mortality remains a major challenge in elderly patients with intertrochanteric hip fractures. Identifying simple and reliable preoperative biomarkers is essential for short-term risk stratification. The blood urea nitrogen-to-albumin ratio (BAR) integrates metabolic stress, renal perfusion, and nutritional status; however, its prognostic value in orthopedic trauma has not been fully clarified. This retrospective cohort study included 514 patients aged ≥ 65 years who underwent surgical treatment for intertrochanteric femur fractures. Preoperative BAR and other inflammatory biomarkers—including CRP-to-albumin ratio (CAR), fibrinogen-to-albumin ratio (FAR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR)—were analyzed. Thirty-day mortality was evaluated using receiver operating characteristic (ROC) analysis and multivariable logistic regression. Thirty-day mortality occurred in 54 patients (10.5%). Non-survivors had significantly higher inflammatory and metabolic biomarker levels and lower albumin levels compared with survivors (all p < 0.05). BAR demonstrated the highest discriminative ability for predicting 30-day mortality (AUC = 0.82), with an optimal cut-off value of 9.0 (sensitivity 79%, specificity 72%). In multivariable analysis, BAR ≥ 9.0 remained the only independent predictor of mortality (adjusted OR 2.68; 95% CI 1.34–5.34; p = 0.006). Preoperative BAR is an independent biomarker for predicting early mortality in elderly patients with intertrochanteric hip fractures. Its simplicity and routine clinical availability support its potential use in preoperative risk stratification. Prospective multicenter studies are needed to confirm these findings.