Original Articles

The Prognostic Value of Using the Duration of Acute Kidney Injury in Cardiac Surgery: An Example Using Two Antifibrinolytics

^* The Dartmouth Institute for Health Policy and Clinical Practice, Section of Cardiology Dartmouth-Hitchcock Medical Center and Dartmouth Medical School, Lebanon, New Hampshire
^† Division of Cardiothoracic Surgery, Maine Medical Center, Portland, Maine
^‡ Department of Medicine, Clinical Epidemiology Research Center, West Haven, Connecticut
^§ Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut

Address correspondence to: Jeremiah R. Brown, PhD, MS, Clinical Research Section, Dartmouth–Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756. E-mail: jbrown@dartmouth.edu

Received: 27 May 2011
Accepted: 6 November 2011

Abstract

Previously, we reported that the addition of duration to the Acute Kidney Injury Network (AKIN) definition of acute kidney injury (AKI) is a marker for more severe kidney injury and predicts long-term mortality. We aimed to evaluate an example of the utility of adding AKI duration to the AKIN definition by comparing the historical use of aprotinin with Amicar. In a single-center observational study, we followed 4987 consecutive patients undergoing cardiac surgery between 2002 and 2007 for postsurgery AKI. Patients with a history of hemodialysis were excluded. Duration of AKI was calculated by the number of days AKI was present as defined by a ≥0.3 (mg/dL) or a ≥50% increase in serum creatinine from baseline or new onset of acute dialysis. Kaplan-Meier and Cox’s proportional hazard modeling was conducted to evaluate 5-year mortality. Fifty-three percent of patients received Amicar (n = 2333) and 47% received high-dose aprotinin (n = 2093). Patients receiving aprotinin had evidence of more advanced disease and comorbidity and were more likely to develop AKI and have longer durations of AKI than Amicar (p < .001): 7.0 ± 11.5 vs. 3.8 ± 6.0 days (p < .001). Nearest-neighbor propensity matching demonstrated aprotinin had significantly worse 5-year mortality compared with Amicar (relative risk [RR] = 2.09, 95% confidence interval [CI] = 1.65–2.65). AKI duration added to the AKIN definition of AKI may provide the necessary sensitivity and specificity for evaluating renal outcomes in clinical trials.