Risk factors and prognostic significance of acute kidney injury in coronary artery bypass graft surgery: Insights from the KDIGO criteria

Purpose: To assess the risk factors and prognostic implications of patients with normal preoperative renal parameters, and who developed acute kidney injury (AKI) following coronary artery bypass grafting (CABG). Methods: This observational study involved 69 patients, who underwent elective isolated CABG with normal preoperative renal function between February 2023 and July 2024, and who subsequently developed AKI within 7 days postoperatively. The association between clinical and demographic characteristics and the outcome was assessed using the Chi-square or Fisher’s exact test. Univariable and multivariable linear regression were used to test for associations between various risk factors and the development of AKI. Results: Total of 57% (n= 39) of patients were >60 years, with male preponderance (77%; n=53). Associated comorbidities included Type 2 diabetes mellitus (77%; n=53), hypertension (62%; n=43), atrial fibrillation (3%; n=2), stroke (9%; n=6), peripheral vascular disease (7%; n=5), anaemia (< 12gm%) (54%; n=37), hypoalbuminemia (52%; n=36)(serum albumin levels < 3.5 gm%), and hyperuricemia (33%; n=23) (serum uric acid level > 7mg%). Hospital mortality was observed in 7 patients (10%) with age >60 years (p=0.02), hypertension (p=0.04), use of CPB (p=0.02), and Stage 2/3 AKI (p=0.00005) being significantly associated. Hemodialysis was required in 4 patients (6%). Multivariate regression identified hyperuricemia as an independent predictor (p=0.02) for development of Stage 2/3 AKI (Odds ratio 42.33; 95% confidence interval 10.24-59.64). Conclusions: Age >60 years, hypertension, on-pump CABG, and development of AKI are risk factors for early mortality in CABG patients. Preoperative hyperuricemia is a significant predictor of postoperative AKI.