Efficacy and safety of app-based remote warfarin management during COVID-19-related lockdown: a retrospective cohort study.

This study aimed to explore the effectiveness, and safety of internet-based warfarin management during the pandemic. In this single-center retrospective cohort study, we compared the safety and efficacy of online warfarin management using a smartphone app (the Alfalfa app) versus conventional outpatient clinic management from January 1, 2020 to March 31, 2020. Patients in the online management group used the Alfalfa app to communicate coagulation test results and other relevant information to a doctor or clinical pharmacist, who then responded with the dose adjustment plan and the date of the next blood test. The outcomes examined were the time in therapeutic range (TTR), incidence of clinical events (i.e., bleeding events, thrombotic events, warfarin-related emergency department visits, and warfarin-related hospital admissions), and the distribution of international normalized ratio (INR) values. Data from 117 patients were analyzed in this study. TTR was significantly higher in the online group than in the offline group (61.0% vs. 39.6%, P < 0.01). Incidence of major bleeding events, thrombotic events, and warfarin-related hospital admissions were comparable between the online and offline groups. However, minor bleeds (5.3% vs. 28.3%, P < 0.01) and warfarin-related emergency department visits (1.8% vs. 23.3%, P = 0.02) were significantly fewer in the online group than in the offline group. The proportion of INR values in the therapeutic range (53.8% vs. 40.1%, P < 0.01) was significantly higher in the online group. Warfarin management using the Alfalfa app appears to be a safe and effective method for warfarin management when patients cannot physically visit hospitals for follow-up.