Effect of Previous INR Control during VKA Therapy on Subsequent DOAC Adherence and Persistence, in Patients Switched from VKA to DOAC

Tessa Elling; Eelko Hak; Jens H Bos; Vladimir Y I G Tichelaar; Nic J G M Veeger; Karina Meijer

doi:10.1055/a-2168-9378

Effect of Previous INR Control during VKA Therapy on Subsequent DOAC Adherence and Persistence, in Patients Switched from VKA to DOAC

Thromb Haemost. 2023 Oct 9. doi: 10.1055/a-2168-9378. Online ahead of print.

Authors

Tessa Elling¹, Eelko Hak², Jens H Bos², Vladimir Y I G Tichelaar^{1

3}, Nic J G M Veeger⁴, Karina Meijer¹

Affiliations

¹ Department of Hematology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.
² Groningen Research Institute of Pharmacy, Unit of Pharmacotherapy, Epidemiology and Economy, University of Groningen, Groningen, The Netherlands.
³ Certe Thrombosis Service, Groningen, The Netherlands.
⁴ Department of Epidemiology, University of Groningen, University Medical Centre, Groningen, The Netherlands.

PMID: 37673103
DOI: 10.1055/a-2168-9378

Abstract

Introduction: Current guideline suggests a switch from vitamin K antagonist (VKA) to direct oral anticoagulant (DOAC) in patients with low time in therapeutic range (TTR < 70%). Poor international normalized ratio (INR) control may be the result of poor compliance, and might therefore be associated with subsequent DOAC intake. Therefore, this study evaluates the effect of previous TTR and other measures of INR control on DOAC nonadherence and nonpersistence, in patients who switched from VKA to DOAC.

Methods: A total of 437 patients who switched from VKA to DOAC between 2012 and 2019 were included using data from Certe Thrombosis Service, IADB.nl pharmacy community database University Groningen, and Statistics Netherlands. DOAC prescriptions were used to determine nonadherence and nonpersistence. INR control (i.e., TTR, time under therapeutic range [TUR], and INR variability) was assessed during the last 180 days of VKA use. Multivariable regression models were applied to determine the association between INR control and DOAC nonpersistence/nonadherence.

Results: On VKA, 67.7% of the patients had a TTR below 70%. DOAC nonpersistence was 39.8% (95% confidence interval [CI]: 33.4-45.5%) during a median follow-up of 34.4 months (interquartile range: 19.1-49.2). Approximately 80% of persistent patients were DOAC-adherent. Low TTR was not associated with DOAC nonpersistence (hazard ratio: 1.14, 95% CI: 0.69-1.87) and DOAC nonadherence (odds ratio: 1.38, 95% CI: 0.67-2.84), nor were TUR and INR variability.

Conclusion: Previous INR control during VKA therapy is not associated with subsequent DOAC nonadherence and nonpersistence. This study suggests that INR control on VKA cannot, and therefore should not, be used for predicting DOAC adherence or persistence.

The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/).