Acute kidney injury is independently associated with higher mortality after cardiac surgery

Abstract

Objectives: To investigate the incidence of acute kidney injury after cardiac surgery and its association with mortality in a patient population receiving ibuprofen and gentamicin perioperatively.

Design: Retrospective study with Cox regression analysis to control for possible preoperative, intraoperative and postoperative confounders.

Setting: University hospital-based single-center study.

Participants: All patients who underwent coronary artery bypass grafting ± valve surgery during 2012.

Interventions: None.

Measurement and main results: Acute surgery within 24 hours of coronary angiography, previous nephrectomy, preoperative sCr >2.26 mg/dL and selective cerebral perfusion during cardiopulmonary bypass were used as exclusion criteria. Acute kidney injury was defined, using the Acute Kidney Injury Network (AKIN) criteria. Six hundred eight patients were included in the study. Mean age was 68.2 ± 9.7 years, and 81% were males. Acute kidney injury was seen in 28.1% of the patients. Overall mortality at one year was 7% and 3% in the no-AKI group. At one year, mortality was 15% in patients with AKIN stage 1 and AKIN stage 2 compared to 70% in AKIN stage 3. A hazard ratio of 2.34 (95% CI: 1.21-4.51, p = 0.011) and 5.62 (95% CI: 2.42-13.06), p<0.0001) were found for AKIN stage 1 and 2/3 combined, respectively.

Conclusions: More than 28% of the patients undergoing elective or subacute cardiac surgery developed AKI in this contemporary cohort. Furthermore, acute kidney injury was an independent predictor of increased mortality irrespective of the perioperative risk factors.

Keywords: acute kidney injury; cardiac surgery; cardiopulmonary bypass; mortality.