Clinical Determinants and Mortality Predictors of Acute Kidney Injury in Neonates: A Five-Year Retrospective Cohort Study

Objectives: Acute kidney injury (AKI) is a frequent and clinically significant complication in critically ill neonates and is associated with increased morbidity and mortality. Although awareness of neonatal AKI has increased in recent years, data on mortality predictors and the trajectory of renal recovery remain limited, particularly in single-center cohorts. This study aimed to comprehensively evaluate the incidence, antenatal, perinatal, and postnatal risk factors, clinical characteristics, and short-term outcomes of neonates diagnosed with AKI in a neonatal intensive care unit, with a particular focus on deaths attributable to AKI during the neonatal intensive care unit (NICU) stay.
Methods: In this single-center retrospective cohort study, the medical records of neonates admitted to the NICU between Janu-ary 2019 and January 2024 were retrospectively reviewed. Neonates diagnosed with AKI according to the KDIGO criteria were included, and relevant demographic, clinical, laboratory, and outcome data were collected. Survivors and non-survivors were compared. Univariate and multivariable logistic regression analyses were performed to identify predictors of mortality, and model performance was assessed using receiver operating characteristic (ROC) curve analysis.
Results: Among 3,456 NICU admissions, 121 neonates (3.5%) were diagnosed with AKI. The mean gestational age was 31.0±5.5 weeks, and 78.5% of patients were preterm. The overall in-hospital mortality rate among neonates with AKI was 30.6%. Sepsis (54.5%) and perinatal asphyxia (40.5%) were common risk factors. Non-survivors had significantly lower gestational age and birth weight and higher serum creatinine levels on postnatal day 7 (p=0.04). In multivariable analysis, sepsis (adjusted OR: 2.64, 95% CI: 1.19–5.86) and serum creatinine on postnatal day 7 (adjusted OR: 7.98, 95% CI: 2.47–25.80) were independent predictors of mortality. The multivari-able model demonstrated good discrimination, with an AUC of 0.857.
Conclusion: Neonatal acute kidney injury-related mortality in the neonatal intensive care unit remains high. In this cohort, sepsis and persistently elevated serum creatinine levels on postnatal day 7 were identified as independent predictors of in-hospital mortality. The observed divergence in creatinine trajectories between survivors and non-survivors highlights the prognostic value of serial renal function assessment for risk stratification. These findings underscore the importance of early identification of high-risk neonates and support the need for future prospective studies to determine whether targeted monitoring and intervention strategies can improve clinical outcomes.

Keywords: Acute kidney injury, mortality, neonatal intensive care unit, neonate, oliguria, polyuria, renal replacement therapy