Self- versus conventional management of oral anticoagulant therapy: effects on INR variability and coumarin dose in a randomized controlled trial

Abstract

Background: Comparison of self-management of oral anticoagulant therapy versus conventional management has been hindered by use of different methods. We tested the hypothesis that there is no difference in the International Normalized Ratio (INR) variability, INR level, and coumarin dose among patients randomized to conventional management versus self-management.

Methods: The study design included uniform analysis of blinded control blood samples in both treatment arms. Ninety-two patients were randomly assigned to either self-management of oral anticoagulant therapy (including a teaching program for self-management followed by 6 months of independent self-management) or 6 months of conventional management. The endpoints were the variance (median square of the standard deviation) of the INR value, the median INR-value (using a blinded control sample analyzed monthly by a reference laboratory), and the coumarin dose.

Results: Self-management was associated with a statistically significant smaller variance in INR values, a higher median INR value, and a higher dose of warfarin compared with conventional management. No difference was found in the group of patients using phenprocoumon.

Conclusion: Training and implementation of patient self-management leads to a smaller variance in INR values, a higher median INR value and a higher dose of coumarin compared with results obtained for conventionally managed patients.