The authors reply
CS-AKI was assigned according to the Acute Kidney Injury Network criteria (5) as originally established (including the 48-hr window), with the greater than 0.1 mg/dL increase in serum creatinine being the sole modification. Furthermore, the majority of CS-AKI occurred within the first 24 hours (93% at University of Michigan and 56% at Boston Children’s Hospital) after surgery. As we describe in our limitations, we did not correct serum creatinine to fluid balance, which Basu et al (6) and others have indicated may underestimate clinically significant CS-AKI (7).
We agree with Liu et al (1) that because we performed a retrospective secondary analysis of data from the SPECS database, we are unable to control for important covariates, including hyper- and hypovolemia, blood loss, anemia, blood product transfusion, deleterious intraoperative and postoperative hemodynamics, and many other possible covariates. This is a well-recognized limitation of retrospective studies in general, and one we acknowledged in our original article (2). Future studies aimed at understanding the mechanisms underlying CS-AKI will need to account for these potential covariates. Nevertheless, our data add to an increasing body of knowledge indicating no support for the use of TGC to prevent CS-AKI in young children undergoing congenital cardiac surgery.