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Virtual Education Effective for Patient Self-Testing for Warfarin Therapy


Warafarin graphic.

By Erika Leemann Price, MD, MPH 

The COVID-19 pandemic put the U.S. healthcare system’s move towards virtual modalities for healthcare delivery into overdrive, with rapid expansion in multiple aspects of telemedicine. While we often think of telemedicine as encounters with primary care or specialty clinicians, ancillary encounters including medication management merit close attention as well. 

Warfarin, a medication used to prevent thrombotic events, requires patients to undergo frequent laboratory testing to ensure that the International Normalized Ratio (INR) stays within therapeutic range to minimize the risk of thromboembolic events or bleeding. Home monitoring or patient self-testing (PST) is well accepted with good outcomes. However, prior to the COVID-19 pandemic, Medicare policies required successful completion of in-person training before initiation of PST. 

The pandemic afforded the opportunity to implement and evaluate virtual training for home-based INR monitoring, following a March 2020 waiver allowing for a temporary transition to virtual training for PST patients. 

Our study in the April issue of The Joint Commission Journal on Quality and Patient Safety compared a cohort of patients who received in-person INR training for PST during the last eight months of 2019 (pre-pandemic) with a cohort who received the same training via virtual format during the last eight months of 2020 (during COVID-19) through Acelis Connected Health Services (ACH).  

ACH receives referrals from clinicians whose patients meet eligibility criteria for PST enrollment, including:

  • use of warfarin for an approved indication
  • stability on warfarin with regular outpatient in-person monitoring for three months prior to enrollment in PST
  • need for INR checks no more frequently than once a week 

Findings Support Virtual Education
We found that the time in therapeutic range (TTR) as calculated by the Rosendaal method improved by two percentage points, from 64.19% to 66.78%, after the transition to virtual training for PST. The statistically significant difference in TTR held across these subgroups:

  • age
  • gender
  • rural vs urban geography
  • indication for warfarin therapy 

While we were not able to evaluate clinical outcomes, there were fewer critical INR values in the virtual versus in-person cohort (4.08% versus 5.03%). Additionally, the overall number of patients referred for PST increased from 13,568 in the in-person sample to 20,115 in the virtual sample. 

The study provides reassurance that virtual training for PST works well for a large group of patients, with an improvement in TTR and a decrease in critical INR values. Our data also suggest that more clinicians are referring patients for PST programs overall. Our findings echo those from other settings in India and Brazil, but this is the largest available evaluation of TTR data in the United States from the COVID era. 

As the healthcare system embraces virtual care modalities, it is critical to identify which specific virtual interventions work well, such as virtual training for PST; these interventions should continue to be supported by professional societies and payor regulations. 

It also is important to recognize that an effective strategy for many patients may not work well for everyone. Participation in PST requires the physical and cognitive ability to access and use home testing and reporting equipment, including the training interface. Patients unable to meet these requirements were not included in this study. 

Another group not represented in this study were patients who were unable to achieve stability on warfarin for three months as required prior to enrollment in PST. While some of this latter group can transition to direct oral anticoagulants (DOACs), some may be unable to do so due to medical considerations or financial constraints. 

As the U.S. population ages, it is important to keep in mind those who have barriers to engagement with virtual health care, while making virtual care interventions as accessible as possible beyond COVID-19.   

Erika Leemann Price, MD, MPH, is an Associate Professor of Medicine at the University of California, San Francisco. She is a hospitalist physician and a consultant for the anticoagulation and thrombosis service at the San Francisco Veterans Affairs Medical Center.