Outcomes of Warfarin Home INR Monitoring vs Office-Based Monitoring: a Retrospective Claims-Based Analysis.

BACKGROUND: Home INR testing (patient self-testing) is feasible and effective for warfarin patients but little is known about real-world differences in outcomes for patients using PST versus laboratory-based INR monitoring. OBJECTIVE: To compare the safety/efficacy of patient self-testing of real-world warfarin therapy versus office/lab-based monitoring of therapy. DESIGN/SETTING/PARTICIPANTS/EXPOSURE: A retrospective claims-based analysis of warfarin patients enrolled in the MarketScan® Commercial Claims and Encounters and Medicare databases between January 1, 2013, and March 30, 2020. Stratification was based on INR testing method: patient self-testing versus testing at physicians' offices/local laboratory. The probability of adverse events in each cohort was determined after adjusting for demographic and baseline clinical characteristics using a repeated measures analysis. MAIN MEASURES: Rates of all adverse events: deep venous thrombosis, pulmonary embolism, bleeding, and stroke. A secondary outcome of interest was emergency department visits. KEY RESULTS: A total of 37,837 patients were included in the analysis: 1592 patients in the patient self-testing group and 36,245 in the office-based therapy group. After adjusting for demographic and baseline clinical characteristics, patients in the office-based group had statistically significantly higher rates of all adverse events (incidence rate ratio [IRR]=2.07, 95% CI [1.82, 2.36]), and specific adverse events including thromboembolism (IRR=4.38, 95% CI [3.29, 5.84]), major bleed (IRR=1.45, 95% CI [1.28, 1.64]), and stroke (IRR=1.30, 95% CI [1.05, 1.61]) than patients in the patient self-testing group. Office-based patients also had a statistically significant higher rate of emergency department visits than patient self-testing patients (IRR = 1.65, 95% CI [1.47, 1.84]). CONCLUSIONS/RELEVANCE: This analysis of real-world claims data shows lower rates of stroke, thromboembolism, and major bleeding, as well as fewer emergency department visits, with patient self-testing compared to office-based/lab INR monitoring. Our finding that PST is safe and effective among current users suggests that more patients may benefit from its use.

Implementation of home-based international normalized ratio testing in adult patients treated with warfarin.

BACKGROUND AND LOCAL PROBLEM: Patients who take warfarin require frequent testing of their international normalized ratio (INR) level to ensure accurate dosage. Frequent testing can be inconvenient for patients in rural settings, the workforce, the homebound, or those who travel. Patients who have a home INR monitor can test their blood remotely. METHODS: To circumvent barriers to INR testing, a quality improvement project was designed to implement home INR testing in an anticoagulation clinic setting. INTERVENTIONS: Patients who received a home INR monitor were compared against two usual care testing arms (laboratory and clinic testing patients) in the outcomes of time in therapeutic range (TTR), adverse events, and patient satisfaction using the Duke Anticoagulation Satisfaction Scale (DASS). RESULTS: The DASS survey demonstrated the home testing patients had a statistically significant advantage over the clinic testing group in the subdomain of hassles and burdens (p = .048), as well as the lowest overall scores (indicating highest satisfaction) over the clinic testing group (p = .041). No patients in the home testing group had clotting or bleeding issues necessitating hospital admission. There were no significant differences between groups in the TTR analysis (laboratory 70.8%, home 68.9%, and clinic 64.5%) (p = .683). CONCLUSIONS: Home INR testing provides convenience for patients and reduces the hassles and burdens of warfarin management, leading to improved satisfaction. This engagement in self-care translates to reduced adverse events. Home INR testing can be used in warfarin patients who are highly motivated and willing to engage in their care.