Trajectory of serum uric acid as a predictor for renal outcome and mortality in stage -3 chronic kidney disease patients
Abstract IntroductionUric acid (UA) is associate with renal and patient survival but the association is causal in nature remains unclear. Also, no finding is yet available regarding longitudinal UA control (trajectory). Methods We enrolled 808 subjects diagnosed with stage 3 CKD from 2007 to 2017. We plotted based on follow-ups the mean UA over a period of 6 months with a minimum of three samples of UA was required. From the sampled points, we generated for each patient an interpolated line by joining mean values of the UA levels over time. And from the lines from all patients, we classified them into three groups of trajectories (low, medium and high UA) through group-based trajectory modeling, and then further separated into either a treatment or no-treatment subgroups. Using the univariate competing-risks regression, we calculated the competing risk analysis with subdistribution hazard ratio of possible confounders.Results All of the 6 trajectories appeared as gradually falling functions with time without any of the curves crossed over one another. For all-cause mortality risk, none of the variables was statistically significant. Patients with DM were statistically more likely to undergo dialysis. There was also a trend that the on-treatment trajectories, compared to their no-treatment trajectories, had lower risks for dialysis.Conclusions Initial treatment of UA is utterly important. Xanthine oxidase inhibitors may lead to renal protection without effects on patient death, independent from the UA-lowering effects. This is the first study on the long-term effects of UA trajectory on patient survivals and renal outcomes.