Cardiovascular safety of febuxostat and allopurinol in patients with gout and cardiovascular comorbidities.
Comprehensive safety evaluation of new drugs for noncardiac indications is needed in the area of cardiovascular (CV) outcomes, particularly in populations with high CV risk such as gout. Febuxostat is a potent nonpurine selective inhibitor of xanthine oxidase approved for the treatment of gout. Long-term CV safety of febuxostat is being established in a randomized, allopurinol-controlled clinical study in patients with gout who have increased CV risk using an analytical approach that provides 90% power to meet a noninferiority margin of 1.3 for the hazard ratio (HR) (febuxostat relative to allopurinol). The primary CV end point for this trial is a composite of CV death, nonfatal myocardial infarction, nonfatal stroke, and unstable angina requiring urgent coronary revascularization. Approximately 7,500 men and women with gout and CV disease are being recruited and will be followed up for up to 5 years postrandomization. The statistical plan for the trial uses a design that evaluates the HR of febuxostat to allopurinol based on the primary CV composite end point when there are a maximum of 624 CV events. Interim analyses will be conducted when approximately 25%, 50%, and 75% of events have occurred. At each analysis, if the upper 1-sided confidence limit of the HR is <1.3, the study will be stopped, and the noninferiority of febuxostat relative to allopurinol with regard to CV risk will be declared. The CARES trial will define the CV safety profile of febuxostat and allopurinol in gout patients at high risk for CV events.