Effect of the Xanthine Oxidase Inhibitor, Febuxostat, on WBC Count in Asymptomatic Hyperuricemia: Subanalysis of the Randomized PRIZE Study.

Aims: The anti-inflammatory effects of the xanthine oxidase inhibitor, febuxostat, a urate-lowering agent, have been reported in animal studies. However, the anti-inflammatory effects of urate-lowering therapy and its associated cardiovascular protective effects have not been fully determined in actual clinical practice. This study aimed to investigate the effect of febuxostat on white blood cell (WBC) count in patients with asymptomatic hyperuricemia and to assess for potential correlations between changes in WBC count and inflammatory biomarkers and atherosclerosis in this patient population.

Methods: This was a post hoc subanalysis of the PRIZE study, a multicenter, prospective, randomized, open-label clinical trial. In the PRIZE study, asymptomatic hyperuricemia patients were randomized to febuxostat group or control group with non-pharmacological therapy and evaluated the effect on vascular. The primary endpoints of this study were the assessment of the time course of WBC count over 24 months and its changes from baseline. Correlations of WBC count with high-sensitivity C-reactive protein (hs-CRP) and mean common carotid artery (CCA)-IMT were also exploratorily examined in the febuxostat group.

Results: A total of 444 patients (febuxostat group, n=223; control group, n=221) with WBC measurements available at baseline and at least one of the follow-up time points of 12 or 24 months, were enrolled. Febuxostat modestly, but significantly, reduced WBC counts at 12 and 24 months compared with the baseline levels (P=0.002 and P=0.026, respectively). Notably, the WBC count in the febuxostat group at 12 and 24 months was significantly lower than that in the control group (P=0.007 and P=0.023, respectively). The changes in WBC count were associated with those of hs-CRP (P=0.038), but not with CCA-IMT (P=0.727).

Conclusions: Febuxostat therapy for 24 months modestly, but significantly, decreased WBC count in patients with asymptomatic hyperuricemia. This might potentially reflect a modest anti-inflammatory action of febuxostat in clinical settings.