Warfarin Patient Self-Management in the US Health Care System: A Nonrandomized Clinical Trial.

Importance: Warfarin patient self-management (PSM) has consistently demonstrated superior efficacy to clinic-based management and is recommended by evidence-based guidelines, but it is virtually unused in the US health care system. Objective: To implement and evaluate warfarin PSM in the US health care system using strategies developed to overcome previously identified barriers associated with PSM underutilization. Design, Setting, and Participants: This was a single-group implementation open-label trial conducted between March 2023 and January 2024 at 4 specialized anticoagulation management services facilities in the US. Patients who participated had been taking warfarin for at least 9 months and were using home international normalized ratio monitors. The follow-up period was 6 months. Data were analyzed between July and December 2025. Intervention: Transition to warfarin PSM using an implementation toolkit developed to address barriers specific to the US health care system. Main Outcomes and Measures: Implementation and clinical outcomes were assessed using the Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) framework and included the proportion of participants successfully transitioned to PSM, time in the therapeutic international normalized ratio range, bleeding and thromboembolic events, and proportion of international normalized ratios managed independently by participants. Results: Of the 255 patients invited to participate in the trial, 138 (54.0%) consented (mean [SD] age, 63.2 [13.2] years; 80 male [58.0%]; 117 White [84.8%]; 123 non-Hispanic or Latino [89.1%]); 127 participants (92.0%) had been receiving warfarin therapy for 2 or more years. Among participants, 120 (87.0%) successfully transitioned to PSM and completed 6 months of follow-up. Compared with baseline, time in therapeutic range during PSM improved from 77.1% (95% CI, 73.7%-80.6%) to 81.3% (95% CI, 78.1%-84.4%). During the PSM phase, 5 bleeding events and no thromboembolic events or deaths occurred. Differences in adverse events in the 6 months before and after PSM initiation were not statistically significant. Most (83.0%) warfarin dosing decisions were made independently by participants and rarely required intervention from clinicians due to safety concerns. At the conclusion of the study, 98 participants (84.4%) expressed a preference for continuing PSM and clinicians expressed comfort with 109 participants (94.0%) continuing PSM. Conclusions and Relevance: In this single-group implementation trial, warfarin PSM was safely and effectively implemented. These results provide critically needed evidence to facilitate and accelerate PSM implementation in the US health care system. Trial Registration: ClinicalTrials.gov Identifier: NCT04766216.