Home-based INR monitoring associated with fewer adverse events
An industry-funded, claims-based analysis found that patients on warfarin who tested their international normalized ratio (INR) at home had lower rates of stroke, thromboembolism, and major bleeding than patients whose INRs were measured at physicians' offices or in laboratories.
Patients taking warfarin may benefit from monitoring their international normalized ratios (INRs) at home, a recent industry-funded study found.
Researchers performed a retrospective claims-based analysis between Jan. 1, 2013, and March 30, 2020, to compare the safety and efficacy of patient self-testing of INRs versus office- or lab-based testing. Data were from both Medicare and commercial insurers. The main outcome measures were rates of deep venous thrombosis, pulmonary embolism, bleeding, and stroke, with ED visits as a secondary outcome. The study was funded by Acelis Connected Health, which offers remote INR monitoring services. Results were published Dec. 15, 2023, by the Journal of General Internal Medicine.
The analysis included 37,837 patients, 1,592 in the self-testing group and 36,245 in the office-based group. The mean age was 60 years, and 55% were male. Patients in the office-based group had statistically significantly higher rates of adverse events overall (incidence rate ratio [IRR], 2.07; 95% CI, 1.82 to 2.36), as well as thromboembolism (IRR, 4.38; 95% CI, 3.29 to 5.84), major bleeding (IRR, 1.45; 95% CI, 1.28 to 1.64), and stroke (IRR, 1.30; 95% CI, 1.05 to 1.61), after adjustment for demographic and baseline clinical characteristics. Patients whose INRs were monitored in the office or a lab also had a statistically significantly higher rate of ED visits than those who self-tested at home (IRR, 1.65; 95% CI, 1.47 to 1.84).
Among other limitations, the authors noted that their study was based on ICD-10 coding and that selection bias was possible, since physicians would be likely to refer their most stable and adherent patients to home monitoring. They concluded that in this analysis of real-world claims-based data, rates of stroke, thromboembolism, major bleeding, and all adverse events were lower in patients who self-tested their INRs at home versus those who received office- or lab-based testing, noting that expert panels have recommended self-testing since 2008.
“Despite the advent of [direct-acting oral anticoagulants], a substantial number of patients continue to receive warfarin. Our finding that [patient self-testing] is safe and effective among current users suggests that more patients may benefit from its use,” the authors wrote.