Association between the Preoperative Estimated Glomerular Filtration Rate and In-Hospital Mortality in Cardiac Surgery Patients in Indonesia: A Multicenter, Retrospective Cohort Study

Background: Acute kidney injury is a common and serious complication after cardiac surgery and is strongly associated with adverse outcomes. The estimated glomerular filtration rate (eGFR) offers a more sensitive assessment of renal function than serum creatinine (SCr). This study aimed to evaluate the association between preoperative eGFR and in-hospital mortality among patients undergoing cardiac surgery. Materials and Methods: This retrospective multicenter cohort study included adult patients who underwent cardiac surgery at four tertiary care hospitals between 2016 and 2020. Preoperative eGFR was calculated using the chronic kidney disease epidemiology collaboration (CKD-EPI) equation and categorized as >90, 30–90, or <30 mL/min/1.73 m 2 . The primary outcome was in-hospital mortality. Multivariable logistic regression was used to adjust for demographic, clinical, and surgical confounders. The discriminative performance of eGFR and SCr was compared using receiver operating characteristic analysis. Results: Among 4771 patients included, in-hospital mortality increased progressively with declining eGFR. Compared with patients with eGFR > 90 mL/min/1.73 m 2 , those with eGFR 30–90 had higher mortality (7.0% vs. 4.1%; adjusted odds ratio [OR]: 1.84, 95% CI: 1.36–2.50), while patients with eGFR < 30 had markedly increased mortality (19.9%; adjusted OR: 5.79, 95% CI: 3.36–9.99). eGFR demonstrated modest but superior discrimination for mortality compared with SCr (area under the curve: 0.615 vs. 0.588; P = 0.001). An optimal eGFR cutoff of <77.6 mL/min/1.73 m 2 was further identified. Conclusion: Lower preoperative eGFR is independently associated with increased in-hospital mortality after cardiac surgery. Although its standalone predictive performance is modest, eGFR is a practical and widely available tool for perioperative risk stratification, particularly in resource-limited settings.