Incidence of Acute Renal Failure in Preterm Babies in a Tertiary Care Centre from Southern India: A Cross-sectional Study

Abstract

Introduction: Preterm babies are a vulnerable population group who are more susceptible to multiple end-organ damage due to an immature immune system and incomplete organogenesis/ organ function. There is scanty data on preterm Acute Kidney Injury (AKI) in India. Aim: To investigate the incidence of acute renal failure and the risk factors predisposing preterm babies to renal failure in an inborn at a tertiary care centre in Southern India. Additionally, we aimed to evaluate the usefulness of a biomarker, Neutrophil Gelatinase Associated Lipocalin (NGAL), as both a marker of renal function and a predictor of AKI in preterm babies. Materials and Methods: A cross-sectional study was conducted in the Neonatal Intensive Care Unit (NICU) at Christian Medical College, Vellore, Tamil Nadu, India, between May 2014 and August 2014. The study included babies born <33 weeks of gestation, while those with abnormal antenatal renal scans, major systemic congenital anomalies, and chromosomal anomalies were excluded. Demographic details and clinical features were noted. Weekly monitoring included urine output, assessment of clinical deterioration, details of interventions, unexpected events, and the use of nephrotoxic drugs. Blood samples for serum creatinine and urine samples for NGAL were collected once a week starting from 72 hours of age. The data was statistically analysed using Statistical Package for the Social Sciences (SPSS) software, version 16.0. Descriptive statistics were reported using mean±SD for continuous variables. Repeated measures Analysis of Variance (ANOVA) and Chi-square test/Fisher’s-exact test were used for categorical variables. Risk factor analysis was done using log binomial to estimate the Relative Risks (RR), considering values greater than 1 as significant. Results: During the study period, a total of 4823 live births were recorded. Among them, 80 babies had a gestational age <32±6 weeks (10.14%). One baby was not recruited as the parents did not provide consent, leaving a total of 79 babies included in the study. Five babies did not complete the study (three died and two were discharged against medical advice). The incidence of AKI in babies <32±6 weeks in this study was 10 out of 79 (12.6%). It was higher in babies <28 weeks, with 4 out of 10 (40%) affected, and all 10 babies (100%) weighed less than 1500 gm at birth. Risk factors for AKI included oliguria, Patent Ductus Arteriosus (PDA), nephrotoxic drugs, low APGAR score, mechanical ventilation, Continuous Positive Airway Pressure (CPAP), and abnormal antenatal scans. Urine NGAL was estimated in 30 babies, and it was found that NGAL levels were high in week 1 or rose by week 2 in those with AKI, while creatinine levels increased in week 2 or 3. NGAL was inversely proportional to gestational age and birth weight. Both NGAL rise and creatinine levels were observed in babies with AKI associated with Non-Steroidal Anti-Inflammatory Drugs (NSAIDS), umbilical lines, and asphyxia. Conclusion: The incidence of AKI was found to be 10%. Although NGAL levels were noted to rise earlier than creatinine levels in those with AKI, a definitive cutoff value for NGAL to define AKI could not be calculated. Due to the small study population, the sensitivity and specificity of NGAL could not be determined.