Previous INR Control and Subsequent DOAC Adherence and Persistence: Are they connected?

Why did you (and your colleagues) write this paper? What was it main purpose?

Poorly taken anticoagulation is a major public health problem as it is associated with increased thromboembolic events, all-cause mortality and higher health care costs. The European Society of Cardiology guideline suggests a switch from vitamin K antagonists (VKAs) to direct oral anticoagulant (DOAC) in patients with low time in therapeutic range (TTR). Low TTR is defined as a value below 70%. However, many physicians worry that TTR and other INR control measures are associated with subsequent poor DOAC intake. Therefore, we evaluated the effect of previous INR control on DOAC non-adherence and non-persistence, in patients who had switched from VKA to DOAC therapy.

What are the main conclusions?

In the 437 patients included in our study, 67.7% of the patients on VKA had a low TTR, as defined as a value below 70%. In our paper, we showed that INR control during VKA therapy is not associated with subsequent DOAC non-adherence nor non-persistence. INR control was assessed by the time in therapeutic range (TTR), time below therapeutic range (TUR) and INR variability. However, overall DOAC non-persistence was high at 39.8% (95% CI 33.4-45.5%) during a median follow-up of 34.4 months [IQR 19.1-49.2]. Approximately 80% of persistent patients were DOAC-adherent.

What are the paper's implications? - to the public? -to medical professionals?

In light of our findings, INR control on VKA cannot, and therefore should not be used for predicting DOAC adherence or persistence. Accordingly, patients with poor INR control on VKA can be suitable candidates for DOAC therapy.

Are the findings clinically significant? Should the findings change practice?

Yes, our findings are clinically significant. We showed that INR control is irrelevant in the decision to switch a patient from VKA to DOAC. We propose a more individual approach in the decision to switch a patient from VKA to DOAC, based on patient characteristics and medical history. Relevant factors in this evaluation could include age, sex, comorbidities, and the duration of anticoagulation therapy, for example.