Acute Kidney Injury After Cardiac Surgery

TLDR

Acute kidney injury after cardiac surgery is a major health issue, and because effective therapies are lacking, modifying risk factors may help prevent it. This study aimed to identify and assess the prognostic importance of modifiable risk factors for AKI after cardiac surgery. Using multivariable logistic regression on a multicenter cohort of 3,500 adult cardiac surgery patients, the authors examined relationships between three AKI severity thresholds and mortality, and sought modifiable perioperative predictors. The study found that 24%, 7%, and 3% of patients met the AKI thresholds, each associated with over fourfold increased odds of death, and that preoperative anemia, perioperative transfusions, and surgical reexploration were independently and strongly linked to AKI, suggesting targeted therapies could reduce this complication.

Abstract

Background— Acute kidney injury (AKI) after cardiac surgery is a major health issue. Lacking effective therapies, risk factor modification may offer a means of preventing this complication. The objective of the present study was to identify and determine the prognostic importance of such risk factors. Methods and Results— Data from a multicenter cohort of 3500 adult patients who underwent cardiac surgery at 7 hospitals during 2004 were analyzed (using multivariable logistic regression modeling) to determine the independent relationships between 3 thresholds of AKI (>25%, >50%, and >75% decrease in estimated glomerular filtration rate within 1 week of surgery or need for postoperative dialysis) with death rates, as well as to identify modifiable risk factors for AKI. The 3 thresholds of AKI occurred in 24% (n=829), 7% (n=228), and 3% (n=119) of the cohort, respectively. All 3 thresholds were independently associated with a >4-fold increase in the odds of death and could be predicted with several perioperative variables, including preoperative intra-aortic balloon pump use, urgent surgery, and prolonged cardiopulmonary bypass. In particular, 3 potentially modifiable variables were also independently and strongly associated with AKI. These were preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration. Conclusions— AKI after cardiac surgery is highly prevalent and prognostically important. Therapies aimed at mitigating preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration may offer protection against this complication.