Comparative effectiveness of allopurinol and febuxostat for the risk of atrial fibrillation in the elderly: a propensity-matched analysis of Medicare claims data.

Abstract

Gout is associated with a higher risk of atrial fibrillation (AF). Comparative effectiveness of allopurinol or febuxostat for reducing the AF risk is unknown, which was our study's main objective. We used the 5% Medicare Beneficiary cohort (≥65 years) from 2006 to 2012 to identify people with a new filled prescription for allopurinol or febuxostat, with a baseline period of 365 days without respective medication and without AF. We used 5:1 propensity-matched Cox regression analyses to assess whether allopurinol use differed from febuxostat use regarding the hazard ratio (HR) of incident AF. We found 25732 eligible episodes in 23135 beneficiaries. Of these, 2311 incident allopurinol or febuxostat use episodes (9%) ended in incident AF with crude incidence rates of 8.0 and 10.5 per 100 person-years, respectively. In propensity-matched analyses, compared with allopurinol, febuxostat was associated with higher HR of AF, 1.25 [95% confidence interval (CI) 1.05-1.48]. Compared with allopurinol <200 mg/day, febuxostat 80 mg/day was associated with significantly higher HR of AF, 1.62 (95% CI 1.16-2.27), but not febuxostat 40 mg/day or higher allopurinol doses. Compared with 1-180 days of allopurinol use, febuxostat use for 1-180 days was associated with significantly higher HR of AF, 1.36 (95% CI 1.10-1.67), but longer durations were not. Febuxostat was associated with a higher risk of AF compared with allopurinol in older adults. Increased AF risk was noted with febuxostat 80 mg/day dose and was most evident in the first 6 months of use. These findings need replication.