Risk factors for perinatal and neonatal mortality in cases with congenital anomalies of the kidney and urinary tract: a nested cohort study.

BACKGROUND

We aimed to investigate predictive factors associated with perinatal and neonatal mortality in cases with congenital anomalies of the kidney and urinary tract (CAKUT).

METHODS

This study included a cohort of neonates with CAKUT born at a tertiary hospital between 1996 and 2021. Controls were matched with CAKUT cases by sex, time, and place of birth at a ratio of approximately 2:1. The covariates included in the analysis were sex, gestational age, birth weight, neonatal classification, and birth order. CAKUT was categorized into four phenotypes: urinary tract dilatation, lower urinary tract obstruction (LUTO), cystic diseases, and agenesis/hypodysplasia. The primary outcome was perinatal and neonatal mortality. Survival analysis was performed using the Cox proportional hazards model.

RESULTS

857 cases and 1,755 controls were included in the analysis. The overall early mortality rate was 7.2%. After controlling for confounding factors, CAKUT cases exhibited a higher risk of perinatal and neonatal mortality than controls (hazard ratio [HR], 25.1; 95%CI, 14.0-45.2). The following covariates were independently associated with mortality: prematurity (HR, 1.7; 95%CI, 1.2-2.5), LBW (HR, 2.4; 95%CI, 1.6-2.5), VLBW (HR, 2.9; 95%CI, 1.1-1.7), oligohydramnios (HR, 3.2; 95%CI, 2.2-4.8), cystic diseases (HR, 3.8; 95%CI, 2.3-6.4), LUTO (HR, 5.1; 95%CI, 3.0-8.5), kidney agenesis/hypodysplasia (HR, 5.1; 95%CI, 2.9-8.7), and extra-renal malformations (HR, 2.6; 95% CI, 1.7-3.9).

CONCLUSIONS

CAKUT was associated with elevated stillbirth and neonatal mortality rates compared with controls. Prematurity, LBW, oligohydramnios, extra-renal malformations, and specific CAKUT phenotypes with kidney involvement were associated with increased mortality risk.