Patients Can Manage Their Own Warfarin Just Fine, Study Suggests

Patients can transition to self-managing their warfarin in the U.S., according to a small feasibility study.

Among 138 patients who agreed to make their own warfarin dosing decisions based on home monitoring, 87% successfully transitioned to patient self-management (PSM) and completed 6 months of follow-up, and time in therapeutic range during PSM improved from 77.1% to 81.3%.

Of note, 83% of warfarin dosing decisions were made independently by patients and rarely required intervention from clinicians, reported Daniel Witt, PharmD, of the University of Utah in Salt Lake City, and colleagues in JAMA Network Open.

There were a total of five bleeding events in the study, and no thromboembolic events or deaths.

“These observations suggest U.S. patients can independently manage warfarin dosing as effectively as their European counterparts,” the authors wrote. “These findings also suggest an opportunity for anticoagulation clinics to optimize resource allocation. By transitioning appropriate patients to PSM, clinics may reduce routine management demands and redirect efforts toward higher-risk individuals and broader antithrombotic stewardship activities.”

Self-managing warfarin is already endorsed by U.S. and European guidelines on the basis of positive randomized clinical trial data, and has been proven to be less burdensome, less expensive, and potentially safer than clinic-based warfarin management for maintaining the international normalized ratio (INR) within a pre-established therapeutic range.

Nevertheless, the in-clinic approach remains the norm in the U.S. due to clinician reluctance and other barriers previously identified by Witt and colleagues.

Thus, the authors devised an approach for warfarin PSM that would most likely be feasible: focus first on people who were clinically stable, had home INR monitors, and had high baseline time in therapeutic INR range to minimize the risk of INR volatility during PSM.

“Our PSM implementation study confirmed that with the right tools, training, and support, similar U.S. patients can successfully engage in PSM,” they wrote. “It is possible that patients using laboratory-based INR testing could also engage in PSM if they had timely access to results through a secure patient portal.”

They recommended that initial PSM recruitment be limited to patients with at least 2 years of warfarin experience who are already using home INR monitors, and that PSM education be delivered via an interactive online module. Furthermore, transition to PSM should include a spotters ready phase (a structured wash-in period for patients to demonstrate sufficient confidence before assuming full responsibility for warfarin decision-making). Finally, patient and clinician comfort with PSM should be reassessed regularly, roughly every 1 to 3 months, they added.

Witt and colleagues tested their strategy of warfarin PSM in a feasibility study conducted at four dedicated anticoagulation management clinics at the University of Michigan, the University of Utah, Brigham and Women’s Hospital, and the Veterans Administration Loma Linda Health System.

Enrollment occurred from March 2023 through January 2024; 255 patients with home INR monitors were invited, of whom 138 consented to the study (mean age 63.2 years, 58% men, 84.8% white).

The PSM approach involved clinical decision tools including an online warfarin dosing tool and manual algorithms. Participants were instructed to contact anticoagulation clinicians in high-risk situations or if they wished to consult with a clinician for any reason.

Ultimately, there was no difference in adverse events before and after PSM initiation.

The majority of patients expressed a preference for continuing self-management at the end of the study (84.4%), and clinicians were comfortable with continuing PSM for 94%.

“Participants appeared confident in their ability to make warfarin dosing decisions, often using their own judgment rather than the provided clinical decision support tools,” Witt and colleagues noted. “Clinical decision support tools may play a greater role for patients with less experience or less stable pre-PSM INR control.”

Older age was the only factor independently associated with less willingness to participate in the PSM implementation study.

Given the small, selected sample and the few participating sites, however, the study did have limited generalizability. For example, no patients receiving warfarin for management of a left ventricular assist device were allowed in the study.