Meta-analysis for outcomes of acute kidney injury after cardiac surgery

This study aimed to investigate the outcomes of acute kidney injury (AKI) after cardiac surgery by the meta-analysis. Electronic databases PubMed and Embase were searched for relative studies from December 2008 to June 2015. For eligible studies, the R software was conducted to meta-analyze outcomes of AKI patients (AKI group) and none-AKI patients after cardiac surgery (NO AKI group). The chi-square-based Q test and I-2 statistic were used for heterogeneity analysis. P<0.1 or I-2 >50% revealed significant heterogeneity among studies, and then a random effects model was used; otherwise a fixed effect model was performed. Egger's test was performed for publication bias assessment. Subgroup analysis was performed by stratifying AKI definitions and study type. Totally 17 studies with 9656 subjects (2331 in the AKI group and 7325 in the NO AKI group) were enrolled. Significantly higher renal replacement therapy (RRT) (OR=23.67, 95% CI: 12.58-44.55), mortality (OR=6.27, 95% CI: 3.58-11.00), serum creatinine (SMD=1.42, 95% CI: 1.01-1.83), and hospital length of stay (LOS) (SMD=0.45, 95% CI: 0.02-0.88) were shown in the AKI group compared with patients in the NO AKI group. Subgroup analysis showed that results of only 3 subgroups were reversed indicating that the definition of AKI did not affect its outcomes. Publication bias was only found among studies involving mortality and serum creatinine, but the 2 outcomes were not reversed after correction. This meta-analysis confirmed the worse outcomes of AKI in patients after cardiac surgery, including higher RRT rates, mortality, and longer hospital LOS than those of NO AKI patients.