The SINGLE-AF randomized trial demonstrates that direct oral anticoagulants (DOACs) cut the risk of serious cardiovascular events by 69% in atrial fibrillation patients with intermediate stroke risk. Led by Professor Boyoung Joung, the study of 1,803 patients in South Korea shows that DOACs significantly reduce ischemic strokes without increasing major bleeding. These findings address a key clinical uncertainty, as observational data show that insurance formulary restrictions on these newer therapies often delay treatment and increase stroke risks.
Results of the SINGLE-AF trial
- ▪The SINGLE-AF trial did not find an increase in major bleeding, which occurred in 0.3% of patients receiving direct oral anticoagulant therapy and 0.5% of those who did not receive anticoagulation.
- ▪In the SINGLE-AF trial, serious cardiovascular events occurred in 0.5% of patients receiving direct oral anticoagulants compared with 1.5% receiving no anticoagulant therapy over a 24-month period, driven by fewer ischemic strokes (0.1% vs 1.1% receiving no anticoagulation).
- ▪The SINGLE-AF randomized trial found a 69% reduction in the primary composite endpoint of stroke, systemic embolism, major bleeding, and cardiovascular death among intermediate-risk atrial fibrillation patients taking direct oral anticoagulants compared to those receiving no anticoagulation.
Design of the SINGLE-AF trial
- ▪The SINGLE-AF trial randomized intermediate-risk atrial fibrillation patients to receive either direct oral anticoagulant treatment with apixaban or rivaroxaban, or to receive no anticoagulation.
- ▪The SINGLE-AF trial, led by Principal Investigator Professor Boyoung Joung of Yonsei University, enrolled 1,803 patients with atrial fibrillation at intermediate risk of stroke across 18 medical centers in South Korea.
Comparison of warfarin and newer anticoagulants
- ▪Non-vitamin K antagonist oral anticoagulants, including dabigatran, rivaroxaban, and apixaban, have demonstrated equivalent or superior efficacy at reducing stroke risk compared with warfarin.
- ▪Historically, treatment with warfarin sodium has been shown to reduce the risk of stroke by up to 70% in patients with atrial fibrillation, but its use is burdened by food and drug interactions and the need for ongoing laboratory testing.
Trends in Medicare Part D coverage
- ▪The percentage of Medicare Part D plans imposing prior authorization or step therapy on non-vitamin K antagonist oral anticoagulants decreased from 41% in 2011 to 26% by 2016.
- ▪By 2013, all Medicare Part D plans in the analyzed longitudinal cohort study sample covered at least one non-vitamin K antagonist oral anticoagulant.
Impact of Medicare Part D restrictions
- ▪A longitudinal cohort study of Medicare beneficiaries found that plans restricting access to non-vitamin K antagonist oral anticoagulants through prior authorization or step therapy were associated with a higher aggregate risk of mortality, stroke, and transient ischemic attack.
- ▪Medicare Part D beneficiaries enrolled in plans that restricted access to non-vitamin K antagonist oral anticoagulants had a lower probability of using those medications, worse adherence, and longer delays in filling initial prescriptions.
Debatable claims
- ▪The SINGLE-AF trial justifies updating global guidelines for intermediate-risk atrial fibrillation
- ▪Intermediate-risk atrial fibrillation patients should routinely receive direct oral anticoagulants
- ▪Open-label clinical trials are reliable enough to guide cardiovascular treatment decisions
- ▪Formulary restrictions on direct oral anticoagulants do more harm than good
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