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

Abstract

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.