Prognostic Value of Serum Uric Acid in Patients on the Waiting List for Renal Transplantation

Abstract

Background: High serum uric acid is associated with increased cardiovascular risk in the general population. Although hyperuricemia is common in patients with chronic kidney disease (CKD), the impact of uric acid on mortality and CV events remains unclear. Objective: We assessed the relationship between base-line serum uric acid and the risk of cardiovascular events and all-cause mortality in a group of patients on the waiting list for renal transplantation before and after renal transplantation. Methods: This was a longitudinal observational study conducted in 1020 hemodialysis patients (54±11 years old, 70% Caucasians, 59% males, 40% diabetics, 38% with CVD, median follow-up 26 months) on the waiting list assessed for cardiovascular risk from July 1999 to June 2011. Data collection was terminated either at the end of the study period or in the moment that the patient had a cardiovascular event or expired. Survival curves were compared by Kaplan-Meier method. 199 patients underwent renal transplantation (50±11 years old, 72% Caucasians, 55% males, 34% diabetics, 26% with associated CVD, median follow-up 19 months). Results: High base-line serum uric acid (≥7.2 mg/dL) was not associated with either CV events (myocardial infarction, stroke, heart failure, sudden death, unstable angina, acute arterial syndrome) or with all-cause mortality. Similar results were observed in subgroups of patients with diabetes, elevated C-reactive protein or associated CV disease. For patients who underwent renal transplantation post-transplant base-line uric acid ≥7.2 mg/dL was associated with increased probability of CV events (p=0.03, HR 1.6, 95% CI 1.03-2,54). Conclusion: Elevated serum uric acid was not predictor of cardiovascular events or death in patients on the waiting list for transplant. However, an increased post-transplant base-line uric acid was related to higher probability of CV events.