Incidence and outcomes of acute kidney injury in the neonatal intensive care unit

Abstract

【Introduction】Acute kidney injury (AKI) is an important complication, especially in critically ill patients. However, studies on AKI in Japanese neonates are few. We report on AKI in a single neonatal intensive care unit (NICU). 【Methods】From September 2007 to August 2010, we investigated neonates admitted to our NICU. AKI was defined using the proposed neonatal AKI classification. Patients were grouped by birth weight：extremely low birthweight (ELBW), very low birthweight (VLBW), low birthweight (LBW), and others. Incidence and outcomes were analyzed using the Cochran-Armitage trend test. Risk factors for AKI were analyzed using the decision tree analysis, and multivariate analysis. 【Results】 We included 1,059 patients (male, 563；female, 496; ELBW, 117; VLBW, 96; LBW, 453; others, 393). Serum Cr levels increased in 14.8%, and urine output decreased in 6.6%. AKI incidence was 14.8% (ELBW, 75.2%；VLBW, 18.9%；LBW, 6.6%；others, 5.3%); 1.2% required dialysis (ELBW, 3.4%; VLBW, 2.1%; LBW, 0.9%; others, 0.8%). Mortality was 4.2% (ELBW, 17.9%; VLBW, 10.4%; LBW, 1.3%; others, 2.0%). Mortality among AKI patients was significantly higher than that among non-AKI patients (18.5% vs. 1.8%), and that among oliguric patients was significantly higher than that among non-oliguric patients (34.3% vs. 5.7%). Inotropic agents, steroid, indomethacin, and gestational age were related to AKI onset. 【Conclusions】 AKI incidence in the NICU was high, especially in ELBW infants. Mortality among AKI patients was significantly higher than that among non-AKI patients. Premature birth, unstable circulatory status, and nephrotoxic drug use were related to AKI onset.