Long-term kidney outcomes in children with posterior urethral valves: a population-based cohort study

Background — Posterior urethral valves represent the most common cause of lower urinary tract obstruction in male infants (∼1/4000 live births). Long-term kidney outcomes of posterior urethral valves remain uncertain. We aimed to determine the time-varying risk of major adverse kidney events (MAKE) following children with posterior urethral valves into adulthood.

Methods — A population-based retrospective cohort study of all males (<2 years) diagnosed with posterior urethral valves between 1991-2021 in Ontario, Canada. Comparator cohorts were: 1) male general population and 2) male pyeloplasty patients (both <2 years). The primary outcome was MAKE (death, long-term kidney replacement therapy [dialysis or kidney transplant], or chronic kidney disease). Time-to-MAKE was analyzed using multivariable-adjusted Cox proportional hazards models. We censored for provincial emigration, or administrative censoring (March 31, 2022).

Results — We included 727 children with posterior urethral valves, 855 pyeloplasty comparators, and 1,013,052 general population comparators. Median follow-up time was 16.6 years (Q1-3 8.6-24.5) overall. Throughout follow-up, 32% of children with posterior urethral valves developed MAKE vs. 1% of the general population and 6% of pyeloplasty comparators. Their adjusted hazard ratio for MAKE was 36.6 (95%CI 31.6-42.4) vs. the general population. The risk of developing MAKE declined over the first 5 years after posterior urethral valves diagnosis but remained elevated for >30-year follow-up. Children with posterior urethral valves were also at higher risk of death, chronic kidney disease, long-term kidney replacement therapy, hypertension, and acute kidney injury than general population or pyeloplasty comparators.

Conclusions — Children with posterior urethral valves are at higher risk of adverse long-term kidney outcomes well into adulthood.