Self-testing and clinical outcomes in Black and White patients on warfarin for atrial fibrillation or venous thromboembolism

Document Type

Article

Publication Date

5-1-2026

Publication Title

Res Pract Thromb Haemost

Keywords

Aged, Aged, 80 and over, Female, Humans, Male, Middle Aged, Anticoagulants, Atrial Fibrillation, Black or African American, Drug Monitoring, Hemorrhage, International Normalized Ratio, Michigan, Registries, Retrospective Studies, Self Care, Treatment Outcome, Venous Thromboembolism, Warfarin, White

Abstract

BACKGROUND: Warfarin management requires frequent international normalized ratio (INR) testing. Self-testing may reduce this burden and improve INR control and outcomes. However, concerns exist about variability in utilization and the effectiveness of self-testing across different patient groups. OBJECTIVES: This study aimed to evaluate INR self-testing utilization and clinical outcomes in Black and White warfarin-treated patients. METHODS: In this retrospective, observational study, Black and White patients who were using warfarin for atrial fibrillation or venous thromboembolism (April 2012 to July 2024) were identified from the Michigan Anticoagulation Quality Improvement Initiative registry. INR control and outcomes were compared between self-testers and non-self-testers. Rates were adjusted by inverse probability weighting; comparisons between racial groups used the negative binomial model. Major and nonmajor bleeding events were defined based on the International Society on Thrombosis and Haemostasis criteria. Moderation analysis examined whether race influences self-testing’s safety and effectiveness. RESULTS: Among 5903 warfarin-treated patients (20.5% Black, 79.5% White), self-testing was used by fewer than 1 in 7 patients (15.3% White, 10.1% Black). Self-testers had higher adjusted time in therapeutic range (TTR; 65.3% vs 59.8%; P < .001), fewer extreme INRs, and lower nonmajor bleeding rates (20.9 vs 29.9 per 100 patient-years; P < .0001) than patients who underwent traditional INR testing. Among Black patients, self-testers had higher TTR (58.8% vs 55.4%; P = .0018) and fewer nonmajor bleeds (23.1 vs 33.1 per 100 patient-years; P = .024) than Black patients who underwent traditional INR testing. Among White patients, self-testers had higher adjusted TTR (68.1% vs 61.3%, P < .0001) and fewer major (3.4 vs 4.9 per 100 patient-years, P = .014) and nonmajor bleeds (16.7 vs 26.2 per 100 patient-years, P < .0001) than White patients who underwent traditional INR testing. Thromboembolic events were similar between groups. CONCLUSION: Self-testing was utilized infrequently, especially among Black patients, but was associated with better INR control and less bleeding than traditional INR testing. Increased utilization and support of self-testing may improve patient outcomes.

Medical Subject Headings

Aged; Aged, 80 and over; Female; Humans; Male; Middle Aged; Anticoagulants; Atrial Fibrillation; Black or African American; Drug Monitoring; Hemorrhage; International Normalized Ratio; Michigan; Registries; Retrospective Studies; Self Care; Treatment Outcome; Venous Thromboembolism; Warfarin; White

PubMed ID

42422772

Volume

10

Issue

4

First Page

106801

Last Page

106801

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