Acute Kidney Injury Is Associated With Higher Morbidity and Resource Utilization in Pediatric Patients Undergoing Heart Surgery

Background The RIFLE (risk, injury, failure, loss, and end-stage renal disease) classification system was developed to standardize the definition of acute kidney injury (AKI) in adults. We hypothesized that AKI was associated with increased mortality and morbidity. Methods Acute kidney injury was defined as a decrease in the amount of estimated creatinine clearance based on pediatric-modified RIFLE (pRIFLE) criteria. Using propensity score analysis, 325 patients who had AKI were matched to 325 patients who did not have AKI from a database of 1,510 consecutive pediatric patients who underwent cardiac surgery between January 2004 and December 2008 at a single center. The association between AKI and outcome was analyzed after propensity score matching of perioperative variables. Results Four hundred eighty-one patients (31.9%) had AKI according to the RIFLE categories. Of those 1,510, 173 (11.5%) reached pRIFLE criteria for risk; 26 (1.7%) reached the criteria for injury; and 282 (18.7%) reached the criteria for failure. Fifty-five patients (3.6%) died. The 2 matched groups were well balanced in terms of measured perioperative variables. Mortality rate was 5.2% in the AKI and 2.5% in the matched control group ( p = 0.09). Occurrence of low cardiac output syndrome ( p = 0.002), need for dialysis ( p < 0.001), and infection ( p = 0.03) were significantly higher, and duration of mechanical ventilation ( p < 0.001) and length of intensive care unit stay ( p < 0.001) were significantly longer compared with the matched control group. Conclusions Acute kidney injury was independently associated with an increased occurrence of postoperative complications but not with mortality after pediatric cardiac surgery.