Experience Always Wins the Day: Measure of Warfarin Anticoagulation Efficiency in the Internal Medicine Clinic

Background: In the real-life setting of a specialized anticoagulation clinic we think that the patient ’ s INRs fall within the therapeutical range most of the time. Our study aimed to assess the time spent by patients treated by Warfarin with INR between 2.0 and 3.0, as well the time spent between 1.5 and 3.5. We chose this new range (1.5 - 3.5) because we think that it is safe and completely acceptable in real-life situation, and requires only minor adjustments to return to treatment goal of 2.0 to 3.0. Methods: A single-center, retrospective observational study was conducted at Hotel-Dieu Hospital, between June 2010 and December 2011. Inclusion criteria were (1) to be treated for venous thromboembolic event with Warfarin, and (2) to have at least 3 INR measurements during the study period. Results: The median duration of follow-up was 281 days with a total number of INR values of 2,553. Median proportion of time at target INR (2.0 - 3.0) was 68.9%. This proportion increased to 98.7% between 1.5 and 3.5. There was a single recurrent thrombosis event, 6 minor bleeding episodes and 10 major bleeding episodes. The majority of major bleeding episodes were caused by gastrointestinal bleeding. Conclusions: We demonstrated that patients followed at a specialized anticoagulation clinic spend on average 68.9% of their time within the therapeutical range of INR and 98.7% of their time within very safe and effective INR values. Indeed, Warfarin is still a valuable treatment for thromboembolic event and a very competitive drug. doi: http://dx.doi.org/10.4021/jh100e