Patient Self-Management of Oral Anticoagulation Guided by Capillary (Fingerstick) Whole Blood Prothrombin Times

Physician management of long-term oral anticoagulation is labor-intensive and costly. Moreover, errors of communication may lead to complications. We assessed the ability of patients to regulate their own therapy based on fingerstick prothrombin times (PTs) in order to avoid these problems. Such management was made possible by the availability of a device capable of measuring a PT from a capillary sample of whole blood. Sixteen patients adjusted their warfarin therapy based on specially developed guidelines for a mean duration of 43 weeks (range, 8 to 92 weeks). Four hundred fifty-eight PTs were measured by patients at home during the entire study. Three hundred ninety-three were in therapeutic range and patients correctly continued their dosages. Of the 65 nontherapeutic PTs, patients made correct dose adjustments in 49 and incorrect adjustments in 16. These incorrect adjustments were minor and judged to be clinically insignificant. They often resulted from a misunderstanding of the dosage guidelines. Given the slow onset of warfarin's effect, the assessment of the PT on a weekly or biweekly basis, and the ability to refine dosage guidelines, these errors were not felt to represent a serious drawback to the concept of warfarin self-management. No complications of therapy occurred during the study. Although this mode of therapy needs further evaluation, this pilot study suggests that patient self-management is feasible and that this model of anticoagulant care offers the potential for improved care at reduced cost.