Serum uric acid levels and long-term outcomes in chronic kidney disease

Abstract

Hyperuricemia is common in chronic kidney disease (CKD), but data regarding the relationship between serum uric acid levels and the long-term outcomes of CKD patients have been limited. The present study evaluated the associations between baseline serum uric acid levels with mortality and end-stage renal disease (ESRD). The subjects of this study were 551 stage 2-4 CKD patients. Cox proportional hazards models were used to evaluate the relationship between serum uric acid tertiles and all-cause mortality, cardiovascular disease (CVD) mortality, 50 % reduction in estimated glomerular filtration rate (eGFR), and development of ESRD, initially without adjustment, and then after adjusting for several groups of covariates. The mean age of the study subjects was 58.5 years, 59.3 % were men, and 10.0 % had diabetes. The mean eGFR was 42.02 ± 18.52 ml/min/1.73 m(2). In all subjects, the mean serum uric acid level was 6.57 ± 1.35 mg/dl, and 52.2 % of study subjects were on hypouricemic therapy (allopurinol; 48.3 %) at baseline. Thirty-one patients (6.1 %) died during a follow-up period of approximately 6 years. There was no significant association between serum uric acid level and all-cause mortality, CVD mortality, development of ESRD and 50 % reduction in eGFR in the unadjusted Cox models. In the adjusted models, hyperuricemia was found to be associated with all-cause mortality and CVD mortality after adjustment with CVD risk factors, kidney disease factors, and allopurinol, but not associated with development of ESRD and 50 % reduction in eGFR. The results of this study showed that hyperuricemia but not serum uric acid levels were associated with all-cause mortality, CVD mortality after adjustments with CVD risk factors, kidney disease factors, and allopurinol in stage 2-4 CKD patients.