Long-Term Consequences of Acute Kidney Injury After Cardiac Surgery: A Systematic Review and Meta-Analysis

Objectives: To determine the effect of acute kidney injury (AKI) associated with cardiac surgery on long-term mortality.

Design: Systematic review and meta-analysis of 9 observational studies extracted from the MEDLINE and EMBASE electronic databases.

Setting: Hospitals undertaking cardiac surgery.

Participants: The study included 35,021 cardiac surgery patients from 9 observational studies.

Interventions: None.

Measurements and main results: Nine studies including 35,021 patients reported incidence of AKI data. The median incidence of AKI was 27.75% (IQR, 16.3%-38.86%). There was significant variation in the reported incidence (range, 11.97%-54%), which can be explained by the different AKI definitions used in the included studies. Eight studies provided adjusted effect size data with 95% confidence intervals on the impact of the occurrence of postoperative AKI and long-term mortality outcomes. Occurrence of postoperative AKI is associated with a significantly increased risk of long-term mortality (HR, 1.68; 95% CI, 1.45-1.95; p<0.00001). Recovery of renal function before hospital discharge is associated with a lower long-term mortality risk (HR, 1.31; 95% CI, 1.16-1.47; p<0.00001) compared with patients who experienced persistent abnormal renal function on hospital discharge (HR, 2.71; 95% CI, 1.26-5.82; p = 0.01).

Conclusions: There is wide variation in the reported incidence of AKI after cardiac surgery, reflecting the different AKI classification systems used. AKI after cardiac surgery is associated with an increased risk of long-term mortality. Patients with persistent renal dysfunction after hospital discharge carry a higher risk of AKI.