Outpatient INR monitoring for patients receiving warfarin during COVID-19 pandemic.
Outpatient INR monitoring for patients receiving warfarin during COVID-19 pandemic.
The need for regular INR testing among patients receiving warfarin to achieve safe anticoagulation is difficult during this time of “social distancing” to minimise the risk of spreading the virus. Hospitals, general practitioner practices and pathology services are minimising patients visits greatly.
The following should be considered during this time to minimise patient contact:
1. Review if a direct oral anticoagulant (DOAC) is a suitable alternative instead of warfarin. DOAC drugs (i.e, apixaban, dabigatran and rivaroxaban) do NOT need monitoring in the same way as warfarin and are approved for the indication of non-valvular atrial fibrillation (AF), and venous thromboembolism (VTE).
Patients who must remain on warfarin and are stably anticoagulated, achieving a time-in-target (TTR) of >60% should be considered for increased intervals of 8 weeks or longer between INR tests.
However, patients with 1) antiphospholipid syndrome (especially triple positive for lupus anticoagulant, anticardiolipin antibody and B2-glycoprotein), 2) mechanical heart valves, 3) renal failure (see THANZ guidelines – Diagnosis and Management of VTE), 4) concomitant drugs that interacts with DOAC, 5) morbid obesity, 6) patients who have had a recurrent thrombo-embolic event whist taking DOAC should NOT be switched to a DOAC.
2. Patients who must remain on warfarin and are stably anticoagulated, achieving a time-in-target (TTR) of >60% should be considered for increased intervals of 8 weeks or longer between INR tests.
Antiplatelet drugs (e.g., aspirin) is not an effective equivalent to anticoagulation.
On behalf of Thrombosis and Haemostasis Society of Australia and New Zealand
(THANZ)