title: The association between the duration of postoperative acute kidney injury and in-hospital mortality in critically ill patients after non-cardiac surgery: an observational cohort study.
abstract: OBJECTIVE
  The severity of acute kidney injury (AKI) has been a well-known predictor for in-hospital mortality. Whether AKI duration could predict in-hospital mortality is not clear. This study determines the association between the in-hospital mortality and AKI duration in patients after non-cardiac surgery.
  
  
  METHODS
  Surgical patients who were admitted to the ICU were enrolled. AKI cases were defined using KDIGO guidelines and categorized according to the tertiles of AKI duration (1st tertile: 2 days, 2nd tertile: 3-6 days and 3rd tertile: 7 days). The adjusted hazard ratios (HRs) for in-hospital mortality are compared to those without AKI. The predictability of mortality is accessed by calculating the area under the curve (AUC) for the receiver operating characteristic (ROC) curve.
  
  
  RESULTS
  From a total of 318 postoperative patients, 98 developed AKI (1st tertile: 34 cases, 2nd tertile: 30 cases and 3rd tertile: 34 cases) and 220 had no AKI. The in-hospital mortality rates are 6.8% (non-AKI), 50% (1st tertile), 46.7% (2nd tertile) and 47% (3rd tertile). The HR's for in-hospital mortality are 7.92, 6.68 and 1.68, compared to the non-AKI group (p = 0.006, 0.021 and 0.476). Cumulative in-hospital survival rates are significantly different for the non-AKI group and the AKI groups (p < 0.001). The AUC for AKI duration and stage together (0.804) is higher than that for AKI stage and AKI duration alone (0.803 and 0.777) (both ps < 0.001).
  
  
  CONCLUSIONS
  In addition to severity, the duration of AKI may be a predictor of in-hospital mortality in patients, after non-cardiac surgery.
authors.affiliation: a Department of Nursing , Chang Gung University of Science and Technology , Taoyuan , Taiwan .|b Division of Nephrology, Department of Internal Medicine , Taoyuan General Hospital, Ministry of Health and Welfare , Taoyuan , Taiwan .
authors.forename: Hung-Chieh
authors.initials: HC
authors.lastname: Wu
authors.affiliation: b Division of Nephrology, Department of Internal Medicine , Taoyuan General Hospital, Ministry of Health and Welfare , Taoyuan , Taiwan .|c Department of Biomedical Engineering , Chung Yuan Christian University , Taoyuan , Taiwan , and.
authors.forename: Wei-Jie
authors.initials: WJ
authors.lastname: Wang
authors.affiliation: d Division of Nephrology, Department of Internal Medicine , Mackay Memorial Hospital , Taipei , Taiwan.
authors.forename: Yu-Wei
authors.initials: YW
authors.lastname: Chen
authors.affiliation: d Division of Nephrology, Department of Internal Medicine , Mackay Memorial Hospital , Taipei , Taiwan.
authors.forename: Han-Hsiang
authors.initials: HH
authors.lastname: Chen
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology* / Q000401:mortality* / Q000503:physiopathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002423:Cause of Death; D015331:Cohort Studies; D016638:Critical Illness / Q000401:mortality / Q000628:therapy; D005260:Female; D017052:Hospital Mortality / Q000639:trends*; D006801:Humans; D007362:Intensive Care Units; D053208:Kaplan-Meier Estimate; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality / Q000503:physiopathology; D016016:Proportional Hazards Models; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D018709:Statistics, Nonparametric; D013514:Surgical Procedures, Operative / Q000009:adverse effects / Q000401:mortality*; D013997:Time Factors; D055815:Young Adult
keywords: Acute kidney injury; KDIGO stages; duration; mortality; non-cardiac surgery