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Comparing Warfarin Dose Decision Making Before and After Transition to Patient Self-Management Jack M.Lawrence1, Geoffrey D.Barnes2, Katelyn W.Sylvester3, Linh Chan4, Sara R.Vazquez5, Aubrey E.Jones1, 5, Spencer J.Gilbert1, 5, Daniel M.Witt1, 5. 1University of Utah College of Pharmacy, Salt Lake City, UT, USA.2University of Michigan, Ann Arbor, MI, USA.3Brigham and Women's Hospital, Boston, MA, USA.4Veterans Affairs Loma Linda Healthcare System, Loma Linda, CA, USA.5University of Utah Health Thrombosis Service, Salt Lake City, UT, USA

Abstract

Background: Evidence-based guidelines recommend warfarin patient self-management (PSM) over clinician-managed care because PSM has been associated with improved anticoagulation control, greater patient autonomy, reduced thromboembolic complications, and lower mortality. Despite these benefits, adoption in the U.S. remains limited. Clinician hesitancy often stems from concerns about patient capability and safety, creating a gap between guideline recommendations and real-world practice. To address these concerns, we conducted a PSM implementation study across four U.S. anticoagulation services. Of 138 patients enrolled, 120 successfully completed 6 months of PSM. Time in therapeutic INR range (TTR) improved significantly after transitioning to PSM. Using the same dataset, we examined whether patients’ dose decision-making and monitoring adherence during PSM were comparable to clinician management. Objectives: To compare warfarin dose decision-making and monitoring adherence during clinician management versus PSM. Methods: Patients using home INR monitors received standardized training on INR testing and algorithm-based dose adjustment before transitioning to PSM. During PSM patients were asked to test INRs every 1 to 2 weeks. We analyzed dose-adjustment behaviors and INR results for the same patients during the 6 months before PSM (clinician managed results) and the 6 months during PSM. Outcomes included: (1) proportion of planned dose changes for out-of-range INRs; (2) absolute percent change in weekly dose for noncritical out-of-range INRs (1.6–4.9); (3) adherence to algorithm-recommended 10–15% dose changes (±5%); and (4) adherence to planned INR recall intervals (±3 days). Wilcoxon rank-sum tests and odds ratios with 95% confidence intervals compared outcomes between periods. Non-significant results were interpreted as evidence of comparable performance. Results: Clinicians planned dose changes for 59.6% of out-of-range INRs (470/789) versus 66.8% during PSM (514/769). Median percent dose change for noncritical INRs was similar (clinician: 7.41% [IQR 5.26–11.11] vs. PSM: 7.69% [IQR 4.76–12.5]; p = 0.79). Odds of algorithm adherence during PSM vs. clinician management were 0.84 (95% CI 0.61–1.16; p = 0.27). INR recall interval adherence was comparable (83.5% vs. 81.9%; p = 0.16). These findings indicate that PSM maintained dosing accuracy and monitoring adherence equivalent to clinician management. Conclusion: Warfarin dose decision-making and monitoring adherence during PSM were comparable to clinician management. Combined with improved TTR, these results support PSM as a safe, guideline-supported option for capable patients. Broader adoption could reduce healthcare burden and empower patients, provided adequate training and support systems are in place. Future research should explore long-term outcomes, cost-effectiveness, and strategies to overcome clinician hesitancy.

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