Best Bang for Your Buck: DOACs vs Warfarin for Atrial Fibrillation

Best Bang for Your Buck: DOACs vs Warfarin for Atrial Fibrillation
Sabrina Wolfe, PharmD, Essentia Health

Background: Since direct oral anticoagulants (DOACs) have gained popularity as guideline-supported therapy, cost has been a major factor in their utility, especially compared to warfarin which is thought to be inexpensive. Now that DOACs have gained popularity, a new question has started to arise. What would be more cost efficient; DOACs or warfarin with lab monitoring? Which of these two options provide a longer survival for patients?  Can the current studies done on this topic be applied to the Veteran Affairs population? With the acceptance and increased use of DOACs in atrial fibrillation (AF), several studies have been completed on the affordability compared to warfarin. However, few studies have been applicable to the Veteran Affairs (VA)- Medicare dual enrolled population.  

Purpose: This study’s purpose was to assess the total medical expenses for nonvalvular atrial fibrillation (AF) patients who were either on a DOAC or warfarin and enrolled in the VA Healthcare System and fee-for-service Medicare. 

Study Design: This nationwide retrospective cohort study looked at data collected between 2012 and 2015 primarily from the VA’s Corporate Data Warehouse which contained care tracking from all VA facilities. The study analyzed 48,297 VA-Medicare dual enrolled patients: 31,276 receiving warfarin and 17,021 patients receiving a DOAC. Total expenditures were presented in table format. Each year was analyzed using a Kaplan-Meier estimator.

Inclusion criteria consisted of those with at least one prescription fill for warfarin or a DOAC within the time period. Exclusion criteria were those without a diagnosis of non-valvular AF or those with missing facility level identifiers. This was done to ensure complete data was being used for VA patients with fee-for-service Medicare. Lastly, those who had switched or discontinued anticoagulants within one year of the index date were excluded. The primary outcome was total medical expenditure over three years following treatment initiation.

Results: Overall, warfarin patients had a higher total healthcare cost than those who were on a DOAC. The cost of medical services were calculated from public payer perspective (VA and Medicare) using health service utilization and prescription drug fills. This held true for both the unadjusted average and three year adjusted expenditures. The study found that those on warfarin had an additional adjusted expenditure of $25,688 (P<0.001). Not only was this discovered, but the study also found that the survival rate was lower among warfarin patients by 0.52 years (95% CI=−0.695 to −0.349). The study noted that the increased cost and lower survival rate was potentially due to higher stroke rate and bleeding events with warfarin use than those on DOACs, which was also demonstrated in previous studies. Two of the prominent limitations with this study were having such a specific population as well as grouping patients based on DOAC class use, not a specific medication. With having the population of the study only contain VA patients, it may not be generalizable to other populations. The limitation with just grouping patients based on DOAC medication class use and not a specific type of DOAC may not accurately capture the expenditure difference from DOAC to DOAC. 

Conclusion: VA patients with nonvalvular AF who are being started on warfarin will incur a higher cost overall than those started on a DOAC. These patients also had a lower survival rate than those on DOACs. 

Key Points: Important outcomes identified included patients on warfarin not only had a higher total overall healthcare cost but they also had a lower survival rate than those on DOACs. When the study assessed expenditures it was done yearly over a three year time span. Lastly, both in adjusted and raw scenarios, DOACs were most cost effective in the long run. 

Reference: 

  1. Wong, E., Done, N., Zhao, M., Woolley, A., Prentice, J. and Mull, H., 2021. Comparing total medical expenditure between patients receiving direct oral anticoagulants vs warfarin for the treatment of atrial fibrillation: evidence from VA-Medicare dual enrollees. Journal of Managed Care & Specialty Pharmacy, 27(8), pp.1056-1066.