Preoperative Urine Albumin-to-Creatinine Ratio Predicts Acute Kidney Injury After Coronary Artery Bypass Grafting

To prospectively evaluate whether baseline urine albumin-to-creatinine ratio (uACR) predicts acute kidney injury (AKI) and postoperative decline in kidney function in elective, isolated coronary artery bypass grafting (CABG) patients and explore the magnitude of effect across clinically relevant uACR strata. Preoperative uACR is a marker of glomerular endothelial dysfunction and systemic microvascular injury that may identify patients at increased risk for AKI after CABG.

In this single-center prospective cohort study, 111 adults undergoing elective, isolated CABG between January 2020 and December 2024 were stratified by baseline uACR (< 30, 30-300, > 300 milligram/gram[mg/g]). The primary outcome was AKI defined by Kidney Disease Improving Global Outcomes creatinine criteria. Secondary outcomes included peak postoperative creatinine, 6-month estimated glomerular filtration rate (eGFR), ventilator duration, and hospital length of stay. Regression models were adjusted for diabetes, hypertension, body mass index, and baseline eGFR. Log-transformations were applied to skewed variables to improve model performance.

The AKI incidence increased across uACR strata: 14.1% (< 30 mg/g), 23.5% (30-300 mg/g), and 66.7% (> 300 mg/g). In adjusted logistic regression (n = 109), each doubling of log-transformed uACR was associated with higher AKI odds (odds ratio 1.44; 95% confidence level 1.03-2.01). Macroalbuminuria (>300 mg/g) conferred a sixfold increase in AKI risk compared with <30 mg/g. Macroalbuminuric patients experienced a 0.75 mg/dL greater rise in postoperative creatinine and a 16.2 mL/min/1.73 m² larger decline in 6-month eGFR. No significant associations were observed with ventilator duration or hospital stay.

In this single center cohort, elevated preoperative uACR, particularly in the macroalbuminuric range, was associated with AKI and early renal dysfunction after CABG and remained an independent predictor after adjustment. Routine preoperative uACR measurement may aid risk stratification and identify patients for nephroprotective strategies; however, these findings require confirmation in larger, adequately powered studies.