Changes in Time in Therapeutic Range Within a Warfarin Anticoagulation Clinic Following Introduction of Direct Oral Anticoagulants

Abstract

Background: As direct oral anticoagulants (DOACs) have become widely recommended as first-line anticoagulation therapy, patients who remain on warfarin are likely those unable to afford, adhere to, or utilize DOAC therapy due to the presence of a contraindication. It is currently unknown how availability of DOACs have affected populations being managed at warfarin (VKA) anticoagulation clinics. Methods: This was a retrospective chart review assessing warfarin-treated patients at an outpatient anticoagulation clinic. The primary endpoint was the 6-month time in therapeutic range (TTR) before and after DOACs were recommended as first-line therapy by clinical guidelines. Study periods were January to June 2015, before DOACs were recommended over VKA, and January to June 2022, when DOACs were often recommended over VKA. TTR, demographic changes, and the presence of contraindications to DOAC therapy in the clinic population between the two time periods were assessed. Results: No difference in 6-month TTR was observed between study periods (59% in 2015 vs 63% in 2022; P = .45). Patient demographics did not significantly vary, which may be due to the clinic retaining 45% of patients between both time periods. Contraindications to DOAC therapy were identified in 39% of the 2015 group and 49% of the 2022 group ( P = .18). The most common contraindication was indication for anticoagulation. Conclusion: Availability of DOACs did not seem to significantly affect the population or management of warfarin-treated patients at an outpatient anticoagulation clinic, however, contraindications and potential challenges to use of DOAC therapy are present in many patients.