Self-managed oral anticoagulation therapy

[Two of the authors respond:]

In our study examining the cost-effectiveness of warfarin self-management1 we incorporated patients with a mechanical heart valve or atrial fibrillation receiving long-term anticoagulant therapy into our model; as such, this is the clinical population of interest. We also stated that warfarin self-management may not be appropriate for all clinical populations receiving long-term anticoagulation therapy. Although this is true, we would like to clarify that for those patients who wish to manage their own therapy, are deemed competent to do so and receive appropriate training, this option is expected to be cost-effective. We also highlight the statement by Fitzmaurice and colleagues that “patients with long-term indication for warfarin should be considered for self-testing or -management.”2

To address the concerns of Jeevan Marasinghe and A.A.W. Amarasinghe that our model did not include patient selection, patient training and product maintenance, we first direct readers to the online Appendix 2 of our article, which shows that we included the costs of patient training, among other things.1 Also modelled were the costs of the device and INR strips, which includes the cost of maintenance and calibration because each device has self-maintenance tools and calibration chips are often included in each box of INR strips. No costs were included for physicians selecting patients because the marginal increase of this fixed cost is negligible.

In the last 2 paragraphs of our Interpretation section, we focused on the 2 limitations of our model. We acknowledged that the results could only apply to those who meet strict criteria. Second, we acknowledged that some patients might prefer physician management over self-monitoring. This latter point was considered in our model through the 20% attrition rate in the self-management arm. As such, we stand by our original conclusions: in patients who are suitable candidates and are willing to perform self-monitoring, this strategy is highly cost-effective.