UC Irvine

Background

Congenital anomalies of the kidney and urinary tract (CAKUT) is associated with a slower progression to end-stage renal disease (ESRD) in pre-dialysis patients. However, little is known about the associated mortality risks after transitioning to dialysis.

Methods

This retrospective cohort study included 0-21 year-old incident dialysis patients from the United States Renal Data System starting dialysis between 1995 and 2016. We examined the association of CAKUT vs. non-CAKUT with all-cause mortality, using Cox regression adjusted for case mix variables. We also examined the mortality risk associated with 14 non-CAKUT vs. CAKUT ESRD etiologies and under stratification by estimated glomerular filtration rate (eGFR).

Results

Among 25,761 patients, the median (interquartile range) age was 17 (11-19) years, and 4780 (19%) had CAKUT. CAKUT was associated with lower mortality, with an adjusted hazard ratio (aHR) of 0.72 (95%CI, 0.64-0.81) (reference: non-CAKUT). In age-stratified analyses, CAKUT vs. non-CAKUT aHRs (95%CI) were 0.66 (0.54-0.80), 0.56 (0.39-0.80), 0.66 (0.50-0.86), and 0.97 (0.80-1.18) among patients < 6, 6-< 13, 13-< 18, and ≥ 18 years at dialysis initiation, respectively. Among non-CAKUT ESRD etiologies, the risk of mortality associated with primary glomerulonephritis (aHR, 0.93; 95%CI 0.80-1.09) and focal segmental glomerulosclerosis (aHR, 0.89; 95%CI, 0.75-1.04) were comparable or slightly lower compared to CAKUT, whereas most other primary causes were associated with higher mortality risk. While the CAKUT group had lower mortality risk compared to the non-CAKUT group patients with eGFR ≥5 mL/min/1.73m², CAKUT was associated with higher mortality in patients with eGFR < 5 mL/min/1.73 m².

Conclusions

CAKUT is associated with lower mortality among children < 18 years old, but showed comparable mortality with non-CAKUT among patients ≥ 18 years old. ESRD etiology should be considered in risk assessment for children initiating dialysis.