Warfarin Dose Requirements in Adults Hospitalized With COVID-19 Infection: A Retrospective Case Series

To describe the impact of hospitalization with COVID-19 infection on warfarin dose requirements in adult inpatients.

A retrospective chart review of 8 adults on warfarin admitted to Michigan Medicine with COVID-19 infection was conducted and reported as a case series. Outcomes of interest were difference in average daily dose of warfarin prior to admission (PTA) and while inpatient (IP), warfarin sensitivity, time in therapeutic range (TTR), confirmed or suspected thromboembolic event, any major or clinically significant bleeding episodes, and in-hospital mortality. IP average daily warfarin doses were lower when compared to PTA average daily doses [1.3 mg (1.3) vs. 6.2 mg (4.1)]. The mean percentage decrease in dose was 68.8% (23) and the mean absolute dose difference was 4.8 mg (4.3). Mean IP percentage tests in range was 30.8% (24.6) and mean IP warfarin sensitivity was 4.2 (3.8), both of which differed from PTA TTR and warfarin sensitivity for those with data available (n = 3, n = 6, respectively). One patient was treated for suspected acute pulmonary embolism while on warfarin and one patient experienced clinically relevant bleeding. In-hospital mortality was zero, mean length of stay (LOS) was 17 days (14.4), and mean intensive care unit (ICU) LOS for the 3 patients requiring ICU level care was 14.3 days (4.5).

Decreased warfarin dose requirements were evident in this group of adults hospitalized with COVID-19 infection. These findings suggest lower doses of warfarin may be needed to achieve therapeutic anticoagulation while inpatient.