The urate-lowering efficacy and safety of febuxostat in the treatment of the hyperuricemia of gout: the CONFIRMS trial

Abstract

Introduction: The purpose of this study was to compare urate-lowering (UL) efficacy and safety of daily febuxostat and allopurinol in subjects with gout and serum urate (sUA) > or = 8.0 mg/dL in a six-month trial.

Methods: Subjects (n = 2,269) were randomized to febuxostat 40 mg or 80 mg, or allopurinol 300 mg (200 mg in moderate renal impairment). Endpoints included the proportion of all subjects with sUA <6.0 mg/dL and the proportion of subjects with mild/moderate renal impairment and sUA <6.0 mg/dL. Safety assessments included blinded adjudication of each cardiovascular (CV) adverse event (AE) and death.

Results: Comorbidities included: renal impairment (65%); obesity (64%); hyperlipidemia (42%); and hypertension (53%). In febuxostat 40 mg, febuxostat 80 mg, and allopurinol groups, primary endpoint was achieved in 45%, 67%, and 42%, respectively. Febuxostat 40 mg UL was statistically non-inferior to allopurinol, but febuxostat 80 mg was superior to both (P < 0.001). Achievement of target sUA in subjects with renal impairment was also superior with febuxostat 80 mg (72%; P < 0.001) compared with febuxostat 40 mg (50%) or allopurinol (42%), but febuxostat 40 mg showed greater efficacy than allopurinol (P = 0.021). Rates of AEs did not differ across treatment groups. Adjudicated (APTC) CV event rates were 0.0% for febuxostat 40 mg and 0.4% for both febuxostat 80 mg and allopurinol. One death occurred in each febuxostat group and three in the allopurinol group.

Conclusions: Urate-lowering efficacy of febuxostat 80 mg exceeded that of febuxostat 40 mg and allopurinol (300/200 mg), which were comparable. In subjects with mild/moderate renal impairment, both febuxostat doses were more efficacious than allopurinol and equally safe. At the doses tested, safety of febuxostat and allopurinol was comparable.

Clinical trial registration: NCT00430248.

Figure 1

Flow of subjects through the study. One subject randomized to allopurinol was not included in the efficacy analyses because baseline serum urate (sUA) did not meet inclusion criterion. The remaining 2,268 subjects eligible for the study comprised the group in which efficacy was assessed.

Figure 2

Proportion of subjects requiring gout flare treatment. Solid lines, open symbols, prior participation in long-term open-label ULT extension trials [13,14]. Dashed lines and closed symbols, no prior participation in long-term open-label ULT extension trials; squares, febuxostat 40 mg daily; circles, febuxostat 80 mg daily; triangles, allopurinol 200/300 mg daily.