JAAOS - 2026-06-15 - Journal Article
Prognostic Role of BUN-to-Albumin Ratio, Albumin-to-ALP Ratio, and Mortality in Critically Ill Patients With Hip Fracture: Analysis of the MIMIC-IV Database, 2008 to 2019.
Chen CH, Chen CL, Li YA, Lo YC
Topics
Key Takeaway
In 265 critically ill hip fracture ICU patients, elevated BUN/albumin ratio independently predicted 1-year mortality (aHR 2.67 for highest tertile vs lowest), while higher albumin/ALP ratio was protective (aHR 0.13).
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Summary
This study evaluated whether admission BUN/albumin and albumin/ALP ratios predict 28-day and 1-year all-cause mortality in critically ill hip fracture patients extracted from the MIMIC-IV database (2008–2019). Multivariable Cox regression showed elevated BUN/albumin independently associated with 1-year mortality (aHR 1.39; highest tertile aHR 2.67), and higher albumin/ALP was protective (aHR 0.13). ROC analysis demonstrated only modest discriminative improvement over existing predictors.
Key Limitation
Single-database retrospective design with only 265 patients limits generalizability and introduces selection bias toward the most critically ill, excluding the broader hip fracture population managed outside the ICU.
Original Abstract
INTRODUCTION
Hip fractures in critically ill patients are associated with high morbidity and mortality. Simple, accessible biomarkers that can predict outcomes are crucial for early risk stratification. This study aimed to evaluate the prognostic value of blood urea nitrogen-to-albumin (BUN/albumin) and albumin-to-alkaline phosphatase (albumin/ALP) ratios in predicting mortality in critically ill patients with hip fractures.
METHODS
This retrospective cohort study included data (including BUN, albumin, and ALP values at admission) of adults with hip fracture admitted to the intensive care unit (ICU) extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Primary outcomes were 28-day and 1-year all-cause mortality. Multivariable logistic regression and Cox proportional hazards models were used to assess associations between BUN/albumin and albumin/ALP and 28-day and 1-year all-cause mortality. Receiver operating characteristic analysis was used to evaluate discrimination.
RESULTS
In total, 265 patients with hip fractures were included. Higher BUN/albumin were independently associated with increased 1-year mortality (adjusted hazard ratio [aHR] = 1.39, 95% CI, 1.06 to 1.82, P = 0.018), with the highest tertile showing significantly greater risk (aHR = 2.67, 95% CI, 1.10 to 6.47, P = 0.030). A higher albumin/ALP was associated with reduced 1-year mortality (aHR = 0.13, 95% CI, 0.02 to 0.81, P = 0.029). Receiver operating characteristic analysis demonstrated only modest improvements in biomarker predictive performance.
CONCLUSION
BUN/albumin and albumin/ALP are independently associated with long-term mortality in critically ill patients with hip fractures and may serve as practical tools for early risk assessment.