The management of oral anticoagulation is fraught with difficulties. This study assessed a new model of anticoagulation management regarding the ability, safety, and efficacy of patients to self-monitor and self-adjust the dose of their oral anticoagulants guided by a capillary whole-blood prothrombin time (PT) monitor.
This investigation is a retrospective cohort study of 20 patients compared with 20 matched control patients receiving oral anticoagulation at a tertiary medical institution.
Study patients monitored their PTs 2153 times during a mean interval of 44.7 months compared with 1608 PTs in matched control patients during a mean interval of 42.5 months. Study patients made an average of 11.5 dosage changes per patient, contrasted with 22.7 changes per control patient (P<.001). The PTs in study patients were within the recommended therapeutic range in 88.6% (95% confidence interval, 87.2 to 89.9) of the determinations compared with 68.0% (95% confidence interval, 65.7 to 70.3; P<.001) of the determinations made by the matched control patients. In response to the 2153 PTs, study patients made 67 (3.1%) dosage decisions that were considered incorrect based on physician guidelines. None of these changes led to adverse outcomes. There was no significant difference in complication rates between the two groups.
Results from what is the first long-term study of patient self-monitoring of PTs and self-adjustment of the warfarin sodium dosage for oral anticoagulation suggest that patients can successfully measure their own PTs, adjust their own warfarin dosage, and achieve a degree of therapeutic effectiveness at least as good, if not better than patients managed in an anti- coagulation clinic. Larger, prospective, randomized trials are needed to confirm the efficacy and safety of this new approach to therapy and to assess its cost-effectiveness.(Arch Intern Med. 1995;155:2185-2189)