Sex differences in the association between urate metabolism and kidney outcomes in patients with chronic kidney disease

Background The association between serum uric acid (SUA) concentration and kidney outcomes in patients with chronic kidney disease (CKD) is controversial. Furthermore, there are no reports regarding the association of clearance of uric acid (CUA) with kidney outcomes. We aimed to determine whether SUA or CUA was associated with kidney outcomes in patients with CKD stratified by sex. Methods The present prospective study was conducted in 815 patients (523 men and 292 women) with CKD. The participants were divided into quartiles (Q1–Q4) of SUA or CUA for each sex. Endpoints were defined as a composite of doubling of serum creatinine (SCr), end-stage kidney disease (ESKD), or death (outcome 1) and a composite of doubling of SCr or ESKD (outcome 2). Results During a median follow-up of 2.5 years, outcomes 1 and 2 occurred in 363 and 321 patients, respectively. Multivariable-adjusted Cox analyses showed that in men, the hazard ratios (95% confidence intervals) for outcome 1 of Q1, Q2, and Q3 of CUA were 2.08 (1.18–3.70), 2.03 (1.22–3.39), and 1.85 (1.17–2.95), respectively, compared with Q4. Additionally, there were similar associations between lower CUA quartiles and outcome 2 in men. However, no associations between SUA and either outcome were observed in men. Conversely, in women, neither SUA nor CUA was associated with an outcome. Conclusion In CKD, lower CUA was independently associated with poor kidney outcomes only in men, and in both sexes, there was no association of SUA with kidney outcomes.