ORIGINAL ARTICLE Epidemiology of cardiac surgery-associated acute kidney injury in neonates: a retrospective study Abdullah AlAbbas & Andrew Campbell & Peter Skippen & Derek Human & Douglas Matsell & Cherry Mammen Received: 10 July 2012 / Revised: 26 February 2013 / Accepted: 26 February 2013 / Published online: 22 March 2013 # IPNA 2013 Abstract Background Cardiac surgery is a known risk factor for acute kidney injury (AKI) in children. However, cardiac surgery- associated AKI (CS-AKI) in neonates has not been well studied. The objectives of this study were: (1) to describe the epidemiology of CS-AKI in neonates utilizing the Acute Kidney Injury Network (AKIN) definition, (2) to identify risk factors for neonatal CS-AKI, and (3) to determine if neonatal CS-AKI is associated with increased morbidity and mortality. Methods This was a retrospective study involving 122 neo- nates (≤28 days) undergoing cardiac surgery from 2006 to 2009. Neonates with and without AKI were identified using serum creatinine (SCr) and urine output (UO) data. Results Cardiac surgery-AKI occurred in 76 (62 %) neo- nates, of whom 22 (29 %) were AKIN stage 1, 19 (25 %) were stage 2, and 35 (46 %) were stage 3. AKI mostly occurred early as 75 % of patients achieved their maximal AKIN stage within the first 48 h post-operatively. In the multivariate analysis, cardiopulmonary bypass duration of ≥120 min was independently associated with AKI [odds ratio (OR) 2.53, 95 % confidence interval (CI) 1.03–6.30]. Severe AKI (AKIN stage 3) was independently associated with mortality (OR 6.70, 95 % CI 1.08–41.50) and a longer stay in the pediatric intensive care unit (hazard ratio 9.09, 95 % CI 1.35–60.95). The majority of severe AKI cases (65 %) were identified with AKIN UO criteria alone without significant rises in SCr. Conclusions Cardiac surgery-AKI is common in neonates when the AKIN definition is utilized and is associated with higher morbidity and mortality, especially in those with more severe AKI. Keywords Acute kidney injury . Neonatal . Epidemiology . Cardiac surgery . Acute Kidney Injury Network Introduction Cardiac surgery-associated acute kidney injury (CS-AKI) in children is common and is a risk factor for poor clinical outcomes, such as increased mortality and prolonged hospital length of stay (LOS) [1–8]. AKI following cardiac surgery is associated with several perioperative factors, in- cluding hypoxemia, cardiopulmonary bypass (CPB), sys- temic inflammation, low cardiac output states, and the use of nephrotoxic medications [1–3, 6–8]. The incidence of pediatric CS-AKI ranges significantly based on the use of various AKI definitions and the age of the study population [1–9]. Even though congenital heart disease is a relatively common condition (prevalence of 6–21 per 1,000 live births) [10–12], with 25 % of cases requiring surgery in the first month of life, little is known about the epidemiology of CS-AKI specifically in the neonatal population. Until recently more than 30 definitions of AKI have appeared in the literature [13]. This has led to an effort to standardize AKI definitions with the development of multidimensional classification systems based on acute changes in serum creatinine (SCr) and/or urine output A. AlAbbas (*) : D. Matsell : C. Mammen Division of Nephrology, British Columbia Children’ s Hospital, 4480 Oak Street, Vancouver, BC, Canada V6H3V4 e-mail: alabbasae@yahoo.com A. Campbell Division of Cardiothoracic Surgery, British Columbia Children’ s Hospital, Vancouver, BC, Canada P. Skippen Division of Critical Care, British Columbia Children’ s Hospital, Vancouver, BC, Canada D. Human Division of Cardiology, British Columbia Children’ s Hospital, Vancouver, BC, Canada Pediatr Nephrol (2013) 28:1127–1134 DOI 10.1007/s00467-013-2454-3