117 - The prevalence and clinical impact of congenital renal anomalies in preterm infants

Poster Number: 117
Publication Number: 117.125

Thomas Hays, Columbia University Vagelos College of Physicians and Surgeons, Brooklyn, NY, United States; Michaela Thompson, NewYork-Presbyterian Morgan Stanley Children's Hospital, New York, NY, United States; David A. Bateman, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Rakesh Sahni, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States; Veeral Tolia, Texas A&M Health Science Center College of Medicine, Dallas, TX, United States; Reese H. Clark, MEDNAX, Myrtle Beach, SC, United States; Ali Gharavi, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, United States

Background: Preterm infants often experience critical illness, but with high variability. Genetic disorders may contribute to this. Congenital anomalies of the kidneys and urinary tract (CAKUT) are often found in preterm infants and strongly associated with genetic disorders. The prevalence of CAKUT in preterm infants is not well described.

Objective: We sought to determine the prevalence of CAKUT in preterm infants, associated characteristics, and association with critical illness.

Design/Methods: This was a multicenter, retrospective study of 408,867 infants, born less than 34 weeks gestation, from 2000-2020 in the Pediatrix Clinical Data Warehouse. Cases were excluded for outborn status or transfer prior to discharge. The presence of CAKUT, other anomalies, and known risks were abstracted. We tested the association of CAKUT (with relevant co-variates) with critical illness (intraventricular hemorrhage (IVH) > grade 3 or periventricular leukomalacia, stage 3 bronchopulmonary dysplasia by Jensen definition, stage 2 or 3 necrotizing enterocolitis (NEC) or intestinal perforation, retinopathy of prematurity requiring surgery, culture positive sepsis, shock requiring pressor, acute kidney injury diagnosed by clinician, need for dialysis, or death).

Results: 323,957 cases met criteria with a mean (SD) gestational age of 30 (3) weeks, birthweight of 1.5 (0.5) kg, and representative proportions of race, ethnicity, and sex. 1.8% of infants had CAKUT. Compared with published descriptions of term infants, preterm infants had an OR of 2.1 (1.8, 2.4) of CAKUT. Lower gestational age or birthweight, male or phenotypically ambiguous sex, known genetic disorders, and extrarenal anomalies were associated with increased risk of CAKUT. CAKUT conferred an adjusted OR of 3.8 (3.5,4.0) of critical illness. At any gestational age, isolated CAKUT or CAKUT with extrarenal anomalies conferred a significantly higher risk of critical illness; from 28 weeks onward, isolated CAKUT or CAKUT with extrarenal anomalies conferred a significantly higher risk of death.Conclusion(s): Our data indicate a higher risk of CAKUT in preterm infants. The causal direction is unclear. Genetic factors that contribute to CAKUT may predispose to preterm birth. Preterm infants at any gestational age with CAKUT were more likely to experience critical illness. The illness most strongly associated was renal failure, however illnesses without a clear causal link, e.g., IVH or NEC, were also more likely in preterm infants with CAKUT. We speculate that CAKUT in preterm infants represents underlying genetic disorders that broadly predispose to critical illnesses.
Figure 1. Odds of CAKUT in preterm versus term infants.Using population-level literature descriptions of infants born at term for comparison, we found that preterm birth was associated with significantly higher odds of CAKUT. This was true for urinary tract dilation or malformation, renal hypodysplasia, and abdominal wall defects (prune-belly syndrome and bladder exstrophy), but not for renal agenesis, ectopy, or fusion.
Figure 2. Odds of critical illness in preterm infants with CAKUT.Following adjustment for known risk factors, the presence of CAKUT was found confer a nearly four-fold increased risk of death or critical illness (AKI, renal failure, stage 3 BPD, grade 3-4 IVH, stage 2-3 NEC, ROP requiring surgery, culture-positive sepsis, or shock requiring pressors).