The Duration of Postoperative Acute Kidney Injury Predicts In-Hospital Mortality in Surgical Patients

Abstract

Backgrounds: It has been known that severity of acute kidney injury can predict in-hospital and long term mortality. Recently, an additional parameter, duration of acute kidney injury (AKI), might allow better prediction of in-hospital mortality. We aimed to determine if duration of AKI adds additional prognostic information in postoperative patients with AKI.

Methods: The study enrolled surgical patients who were admitted to the intensive care unit. AKI cases were defined by RIFLE (risk, injury, failure, loss and end-stage renal failure) criteria and categorized according to tertiles of AKI duration: first tertile, less than 1 day; second tertile, 2 - 5 days; third tertile, greater than or equal to6 days. The hazard ratios (HRs) for in-hospital mortality after adjust multiple covariates compared to those without AKI were recorded. The predictability of mortality was accessed by calculating the area under the curve (AUC) of receiver operating characteristic curve.

Results: In total, 504 postoperative patients with 377 developed AKI (firsttertile: 124 cases, second tertile: 140 cases, third tertile: 113 cases) and 127 without AKI were enrolled. The overall in-hospital mortality was 39%. The in-hospital mortality rates were 15.7% (non-AKI), 28.2% (first tertile), 55% (second tertile), and 38.3% (third tertile) as well as the HRs for in-hospital mortality were 1.632, 2.956 and 2.212 compared to non-AKI group (P = 0.201, 0.010 and 0.040). Cumulative in-hospital survival rates differed significantly for non-AKI group vs. AKI groups (first, second and third tertile) (P < 0.001 by log-rank test). The AUC of AKI duration and stage together (0.696) was higher than AKI stage alone using RIFLE criteria (0.665) (both P < 0.001).

Conclusions: AKI duration was an additional predictor of in-hospital mortality in patients with postoperative acute kidney injury.




World J Nephrol Urol. 2014;3(1):18-24
doi: http://dx.doi.org/10.14740/wjnu143w