Abstract P260: Superior Oral Anticoagulation Management With Self Testing and Automated Online Management; An Interim Analysis

Abstract

Background: The safety and efficacy of warfarin therapy is critically dependent on control of the international normalized ratio (INR). One-third of 3,587 warfarin-treated patients with their INR time in the therapeutic range (TTR)> 75% had a 50% lower major event rate compared to the one-third whose TTR was < 60%. Objective: Assess the impact of three interventions on INR control and management time. Interventions included weekly INR self testing, daily low dose vitamin K, and online management. Methods: Sixty-three patients who were at least 18 years of age, had completed at least 7 months of warfarin therapy, and did not have a diagnosis of antiphospholipid antibody or HIV/AIDS provided written informed consent. INR control was assessed for 6 months pre-study and for up to 12 months during the study. INR control was reported as %TTR, %TTR +/- 0.3 INR units, and % time at an INR below 1.5 or above 5. Clinician time required for each “virtual visit” was recorded and 1 minute was assigned for each automated visit. Results: Eight of 63 patients were excluded (4 withdrew consent the first week, 3 were early protocol violaters, and 1 had warfarin discontinued at study day 11). Fifty-five patients provided 26.83 patient-years of pre-study data during which the TTR was 56.83%, TTR +/-0.3 INR units was 82.55%, and time below 1.5 or above 5 was 2.41% and 0.09%, respectively. Of 54.14 patient-years of study data, TTR improved to 79.65% TTR, 93.57% for TTR +/-0.3 INR units, and 0.4% and 0.07% for time below an INR of 1.5 or above 5, respectively (see Table ). Clinician management required 8.94 minutes per 4 “virtual visits” per patient per month. Summary: Weekly INR self testing, daily low dose vitamin K, and online automated management improved the TTR by 22%; a degree of improvement that has been associated with a 50% reduction in stroke, heart attack, major bleeding, and death. INRs were rarely very far out of range and management required clinician time of less than 10 minutes per patient per month. INR Control Pre-Study vs Study Period End Point Pre-Study n=55, 26.83 patient-years Study, n=55, 54.14 patient-years % Time in Range 56.83 79.65 % Time in Range +/- 0.3 INR units 82.55 93.57 % Time INR < 1.5 2.41 0.40 % Time INR > 5 0.09 0.07 # (%) Patient with TTR > 75% 11 (20) 39 (70.1) # (%) Patients with TTR +/- 0.3 INR > 75% 17 (30.1) 55 (100) # (%) Patients with TTR < 60 30 (54.5) 4 (7.3) # (%) Patients with TTR +/- 0.3 INR < 60% 7 (12.7) 0 (0.0)