Association of Serum Uric Acid-Lowering Therapy and Resistance Index After Renal Transplantation

Hyperuricemia is a frequent problem after renal transplantation. It is associated with an increased risk of cardiovascular events and graft loss. In the present study, we evaluated whether treatment of hyperuricemia is associated with intrarenal hemodynamic changes as measured by the resistance index (RI).

We performed a retrospective analysis of 402 patients who underwent renal transplants over a follow-up period of 120 months. The population was stratified into three groups based on examinations at month 12 after transplantation. Group 1 (normouricemia) had a serum uric acid (SUA) concentration <7 mg/dL and never received SUA-lowering therapy during follow-up. Group 2 (hyperuricemia, untreated) had a SUA≥7 mg/dL and never received SUA-lowering therapy. Group 3 (hyperuricemia, treated) received SUA-lowering therapy within the follow-up period.

At 12 and 60 months, linear regression analysis was performed between RI and SUA concentrations showing a significant correlation for this group at month 12. The development of RI within the 10-year follow-up period differed among groups: At month 120, RI was significantly higher in subjects with hyperuricemia that was untreated (0.76 ± 0.06) than in the other groups (P < 0.05), although it started at a level even lower than the group of subjects with hyperuricemia that were treated at 12 months (0.70 ± 0.08 vs. 0.73 ± 0.08, P < 0.05). In cox regression analysis adjusted for age, eGFR, body mass index, and postmortal versus living donation, there was a trend to better survival in Group 3.

SUA-lowering therapy is associated with a lower increase of RI over time and a trend to better survival of recipients of renal transplants in this retrospective analysis.