Efficacy of xanthine oxidase inhibitor for chronic kidney disease patients with hyperuricemia

Background Hyperuricemia is a known risk factor for end-stage renal disease. Although xanthine oxidase (XO) inhibitors are expected to protect the kidney function, evidence to this end is insufficient at present. Methods This study was a multi-center, open-labeled, randomized study conducted in Mie Prefecture in Japan. Patients were included if they were between 20 and 80 years old and had a serum uric acid (sUA) level >= 7.0 mg/dl with or without gout, estimated glomerular filtration rate (eGFR) of 15-60 ml/min/1.73 m(2), and urinary protein creatinine ratio (uPCR) of 0.15-3.5 g/gCr. Patients were randomly assigned to a Topiroxostat or Febuxostat group, and the treatment target for the sUA level was < 6.0 mg/dl. The primary outcome was the change in the uPCR after 24 weeks. Results The change in the median uPCR after 24 weeks was not statistically significant after treatment in the Topiroxostat or Febuxostat group (0.05 g/gCr and - 0.04 g/gCr, respectively). However, the sUA levels decreased significantly in both groups (Topiroxostat group: 8.6 +/- 1.1 at baseline to 6.0 +/- 1.1 mg/dl at 24 weeks, Febuxostat group: 8.4 +/- 1.1 mg/dl at baseline to 5.9 +/- 1.3 mg/dl at 24 weeks). No significant change in the eGFR after 24 weeks was noted in either the Topiroxostat or Febuxostat group (- 0.04 +/- 4.59 ml/min/1.73 m(2) and 0.31 +/- 4.70 ml/min/1.73 m(2), respectively). Conclusions In this study, XO inhibitors did not significantly reduce the uPCR in chronic kidney disease stage 3 and 4 patients with hyperuricemia.