Acute kidney injury after coronary artery bypass grafting and long-term risk of end-stage renal disease

Abstract

Background: Acute kidney injury (AKI) is a common complication after coronary artery bypass grafting (CABG) and is associated with adverse outcomes. However, the relationship between AKI after CABG and the long-term risk of end-stage renal disease (ESRD) is unknown.

Methods and results: This study included 29 330 patients who underwent primary isolated CABG in Sweden between 2000 and 2008. AKI was classified according to the Acute Kidney Injury Network (AKIN) classification: stage 1, >0.3 mg/dL (>26 μmol/L) or 50% to 100% increase; stage 2, 100% to 200% increase; and stage 3, >200% increase from the preoperative to postoperative serum creatinine level. Cox proportional hazards regression analysis was used to calculate hazard ratios with 95% confidence intervals for ESRD in AKIN stage 1 and stage 2 to 3. Postoperative AKI occurred in 13% of patients. During a mean follow-up of 4.3±2.4 years, 123 patients (0.4%) developed ESRD, including 50 (1.6%) in AKIN stage 1, 29 (5.2%) in AKIN stage 2 to 3, and 44 (0.2%) without AKI after CABG. After multivariable adjustment, the hazard ratio for ESRD was 2.92 (95% confidence interval, 1.87-4.55) for AKIN stage 1 and 3.81 (95% confidence interval, 2.14-6.79) for AKIN stage 2 to 3.

Conclusions: This nationwide study of patients who underwent CABG found that a small increase in the postoperative serum creatinine level was associated with an almost 3-fold increase in the long-term risk of ESRD after adjustment for a number of confounders, including preoperative renal function.

Keywords: acute kidney injury; coronary artery bypass; epidemiology; kidney failure, chronic; prognosis.