Background: Self-management (SM) of warfarin by patients is an attractive strategy, particularly if it improves anticoagulation control and can be done safely under minimal physician supervision.
Objective: To compare the effect of SM with physician-management (PM) on the maintenance of therapeutic anticoagulation.
Methods: A randomized, open-label eight-month trial was performed. Patients 18 years of age and older were eligible if they were receiving warfarin for at least one month before enrolment and required anticoagulation for at least one year to a target international normalized ratio (INR) of 2.0 to 3.0 or 2.5 to 3.5. Exclusion criteria were a known hypercoaguable disorder, mental incompetence, a language barrier or an inability to attend training sessions. Patients randomly assigned to SM tested their INR using a point-of-care device (Pro Time Microcogulation System, International Technidyne Corporation, USA) and adjusted their warfarin doses using a nomogram. Patients randomly assigned to PM received usual care from their general practitioner. The primary outcome was to demonstrate 20% improvement in anticoagulation control by SM.
Results: One hundred forty patients were randomly assigned (70 per group). Thirteen patients dropped out of SM early due to an inability to self-manage. Based on intention-to-treat analysis, there was no difference in the proportion of INR in range (SM 64.8% versus PM 58.7%, P=0.23) or time in target range (SM 71.8% versus PM 63.2%, P=0.14). Patients managing their own therapy spent less time below the therapeutic range (15.0% versus 27.3%, P=0.04). There were three major complications of thrombosis or bleeding, all occurring in the PM arm. All patients who completed SM preferred to continue with that strategy.
Conclusions: SM was not significantly better than PM in maintaining therapeutic anticoagulation. SM was feasible and appeared safe in the present study population.