Impact of increased patient out-of-pocket costs on oral anticoagulant discontinuation among Medicare beneficiaries with atrial fibrillation treated with apixaban

Objective To characterize the change in apixaban out-of-pocket (OOP) costs from 2016 to 2017 (after a formulary tier increase) and to assess the association between increased OOP costs and treatment discontinuation among Medicare beneficiaries with atrial fibrillation (AF).Methods Medicare fee-for-service claims data (2012-2019) were used to conduct a retrospective cohort study on adult patients with AF who experienced an increase in apixaban OOP costs from 2016 to 2017 due to formulary tier increase. Discontinuation was defined as apixaban treatment gap of >30 consecutive days without switching to another oral anticoagulant. Multivariable Cox proportional hazards models were used to identify factors associated with treatment discontinuation.Results Among 1,153 patients treated with apixaban who experienced increased OOP costs from 2016 to 2017, 321 (27.8%) discontinued treatment in 2017 (mean age 78.3 years, 58.9% male, 92.8% White, 38.6% from the South). From 2016 to 2017, the mean (standard deviation) OOP costs for apixaban increased from $76.61 ($40.75) to $162.41 ($60.16) per month (mean change: $85.80 [$57.12]), which was significantly higher among patients who discontinued treatment than those who did not ($93.42 [$61.40] vs $82.87 [$55.13], respectively; p < 0.05). After multivariable adjustment, each $50 increase in monthly OOP costs was associated with a 1.27 times higher likelihood of treatment discontinuation (p < 0.05).Conclusion Following the formulary tier increase of apixaban from 2016 to 2017, increases in OOP costs was associated with a significantly higher probability of treatment discontinuation among Medicare beneficiaries with AF.