Acute Kidney Injury After Coronary Artery Bypass Grafting and Long-Term Risk of End-Stage Renal Disease

Rydén L, Sartipy U, Evans M, et al.
Circulation. 2014;130:2005-2011

Background

Coronary artery bypass grafting (CABG) is frequently followed by acute kidney injury (AKI) and adverse outcomes [1,2]. Patients with AKI, in various patient groups, are at increased risk of end stage renal disease (ESRD) [3-7]. It is unknown, however, whether AKI after cardiac surgery increased the long-term risk of ESRD.
The present study, firstly, investigated the long-term risk of ESRD in patients who developed postoperative AKI after primary isolated CABG. Secondly, the potential effects of preoperative renal function and gender were examined. The nationwide cohort included 29.330 patients who underwent CABG in Sweden between 2000 and 2008. AKI stages 1, 2, and 3 were classified based on pre to postoperative changes in serum creatinine levels according to the Acute Kidney Injury Network (AKIN) classification.

Main results

• Postoperative AKI occurred in 13% of patients.
• 0.4% (123 patients) developed ESRD after CABG during a mean follow-up of 4.3±2.4 years, of whom:  
  - 50 (1.6%) were in AKIN stage 1; 29 (5.2%) in stage 2 to 3, and 44 (0.2%) were free of AKI
  - 82 (67%) started haemodialysis, 40 (33%) started peritoneal dialysis, and 1 (0.8%) underwent kidney transplantation
• After multivariable adjustment, HR for ESRD was 2.92 (95%CI: 1.87–4.55) for AKIN stage 1 and 3.81 (95%CI: 2.14–6.79) for AKIN stage 2 to 3.
• 15% of the patients died. Death or ESRD occurred in 3554 patients (14%) without AKI, in 840 patients (27%) in AKIN stage 1, and in 216 patients (38%) in AKIN stage 2 to 3.
• There was no evidence for a significant renal function–by–sex interaction (P=0.515).
• No evidence was found for a significant preoperative renal function–by–AKI interaction for the outcome of ESRD (P=0.523) or ESRD or death (P=0.080).

Conclusions

This nationwide observational study of patients who underwent CABG showed that a small postoperative increase in serum creatinine levels was related to an almost three-fold increase in the development of ESRD for up to 9 years after surgery, after adjustment for a number of confounders, including preoperative renal function. The absolute risk of ESRD was small.

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