Monitoring oral anticoagulant therapy by telephone communication

The number of patients who need supervision during oral anticoagulant treatment is growing constantly. We have presently enrolled 156 patients who were referred to our anticoagulant clinic and who were taking sodium warfarin with target International Normalized Ratios (INR) of low (2-3), intermediate (2.5-3.5) and high (3-4) range. Patients performed the tests in laboratories situated in locations at their convenience and received further instructions from a specialist via telephone communication. A total of 8758 prothrombin times (5214, 1947 and 1597 tests for individuals in the low, intermediate and high range, respectively) were performed over the period of 3.16 +/- 2.6 years (range, 6 months-9.5 years) and reported to the specialist. It was found that in the aforementioned three groups of intensity 63.3, 57.0 and 47.7% of the INRs were within the target range, the respective percentages for the expanded (+/- 0.5) target INR being 92.8, 87.8 and 78.5%. The INTERDAY software was used to calculate the number and proportion of days within the target INR range, the respective results being 71.0, 64.0 and 51.6% and 96.2, 93.2, 86.4% for the expanded range. The number and percentage of bleeding and embolic complications' referrals to the emergency room and hospitalizations were similar to those reported for anticoagulant clinics in which patients have to actually pay a personal visit in order to receive instructions. Our study is significant in that it documents that trans-telephonic communication is feasible safe and cost-effective and that the clinical results are at least as good as those obtained by traditional consultation.