Pilot study of a novel patient self-management program for warfarin therapy using venipuncture-acquired international normalized ratio monitoring

Abstract

Study objective: To compare clinical and safety outcomes of warfarin therapy before and after implementation of a novel patient self-management (PSM) program in which patients received their venipuncture-derived international normalized ratio (INR) results through a secure online messaging system and adjusted their warfarin dosages and follow-up visits according to provided support tools.

Design: Prospective, open-label, 3-month, pilot study.

Setting: Centralized clinical pharmacy anticoagulation service.

Patients: Forty-four patients with atrial fibrillation who were receiving warfarin for more than 6 months were enrolled in the trial between January 1, 2011, and February 28, 2011; 39 patients completed the trial. Patients acted as their own controls.

Intervention: Patients received dosing decision support tools during a 2-hour live PSM training class. Those who then demonstrated proficiency in PSM assumed responsibility for their warfarin therapy management.

Measurements and main results: Outcomes of warfarin therapy were measured in each patient before and after implementation of the PSM program. Study variables included time in the therapeutic INR range (TTR), numbers of INR tests performed, and episodes of major bleeding or thrombosis. No significant difference in TTR occurred between the 90 days before PSM program participation and the 90 days of PSM (82.9% vs 81.2%, p=0.65). The mean number of INR tests performed for each patient increased from 2.97 before PSM program participation to 4.38 during PSM (p<0.01). No bleeding or thrombotic events occurred during the PSM phase.

Conclusion: Patients were trained to engage in PSM using support tools and venipuncture-derived INR results received by an online messaging system to adjust warfarin dosage and frequency of INR testing. No significant difference in TTR occurred in these patients before and during the PSM. This novel PSM model appears to be a feasible method of managing warfarin therapy in carefully selected patients; however, a larger, randomized controlled trial is needed to evaluate the safety and efficacy of the model and its effect on anticoagulation service workload.