Abstract
RATIONALE & OBJECTIVE: Clinical trials have shown that serum uric acid reduction does not slow chronic kidney disease (CKD) progression in adults, but it is uncertain whether these findings apply to children. STUDY DESIGN: An observational cohort study. SETTING & POPULATION: The Chronic Kidney Disease in Children cohort with participants who initiated allopurinol with a comparison group matched on age, sex, uric acid, CKD diagnosis, estimated glomerular filtration rate (eGFR), and proteinuria. EXPOSURE: Allopurinol initiation. OUTCOMES: Uric acid, eGFR, and proteinuria before and after initiation, and longitudinal changes over time. ANALYTICAL APPROACH: Allopurinol initiators were matched to noninitiators at a 1:3 ratio. Nonparametric tests compared levels before and after initiation and within-person changes. Linear mixed effects models characterized baseline and longitudinal differences between treatment groups. RESULTS: A total of 27 participants initiated allopurinol, and these were matched to 81 participants who did not initiate allopurinol. Allopurinol was associated with a 15.9% lower serum uric acid (95% CI, -21.1% to -10.4%) relative to the matched comparison group (P < 0.001) after initiation. There were no significant differences in eGFR or proteinuria over time by group. LIMITATIONS: Observational study designed for comparative effectiveness and relatively small sample size; effectiveness of allopurinol initiated at lower levels of uric acid could not be estimated. CONCLUSIONS: Allopurinol was effective at significantly lowering serum uric acid in children with CKD but was not associated with CKD progression measured by longitudinal eGFR and proteinuria.