The Impact of Polypharmacy on the Effectiveness and Safety of Non-vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation.

Background:  Polypharmacy may affect outcomes in patients with atrial fibrillation (AF) using non-vitamin K antagonist oral anticoagulants (NOACs) or vitamin K antagonists (VKAs) due to interactions or reduced adherence, but comparative data are lacking. Therefore, the impact of polypharmacy on AF-related outcomes and benefit-risk profiles of NOACs in patients with polypharmacy were investigated.

Methods:  AF patients initiating anticoagulation between 2013 and 2019 were included using Belgian nationwide data. Inverse probability of treatment weighted Cox regression was used to investigate outcomes.

Results:  Among 254,478 AF patients, 167,847 (66.0%) used ≥5 drugs. Polypharmacy was associated with higher stroke or systemic embolism (stroke/SE) (adjusted hazard ratio [aHR]: 1.08, 95% confidence interval [CI]: 1.02-1.15), all-cause mortality (aHR: 1.45, 95% CI: 1.40-1.50), and major bleeding risks (aHR: 1.29, 95% CI: 1.23-1.35). Among patients with polypharmacy, NOACs were associated with lower stroke/SE (aHR: 0.68, 95% CI: 0.63-0.73), all-cause mortality (aHR: 0.80, 95% CI: 0.77-0.84), major bleeding (aHR: 0.92, 95% CI: 0.87-0.97), and intracranial bleeding risks (aHR: 0.77, 95% CI: 0.69-0.85), but higher gastrointestinal bleeding risks (aHR: 1.10, 95% CI: 1.01-1.19) compared to VKAs. Major bleeding risks were lower with apixaban (aHR: 0.79, 95% CI: 0.74-0.85), but nonsignificantly different with other NOACs compared to VKAs. Lower major bleeding risks were observed with dabigatran (aHR: 0.91, 95% CI: 0.85-0.97) and apixaban (aHR: 0.77, 95% CI: 0.73-0.81) compared to rivaroxaban, and with apixaban compared to dabigatran (HR: 0.83, 95% CI: 0.77-0.90) and edoxaban (HR: 0.77, 95% CI: 0.70-0.85).

Conclusion:  Polypharmacy was associated with increased thromboembolic, bleeding, and mortality risks in AF patients. NOACs had better benefit-risk profiles than VKAs in patients with polypharmacy.