Empowering Patients to Monitor and Manage Oral Anticoagulation Therapy

Oral anticoagulation management has undergone a number of improvements since the discovery and first clinical use of dicumarol in the early 1940s. In this issue of THE JOURNAL, Sawicki¹ describes a model of anticoagulation management that introduces the next phase in this evolution, a model of patient self-management made possible by point-of-care PT monitoring.

Since the introduction of point-of-care PT instruments more than 10 years ago,² a number of instruments have become available or are in development that determine a PT-INR measurement equivalent by activating capillary whole blood with tissue thromboplastin. The end point of clotting is determined by assessing the movement of blood cells or oscillating iron particles or by assessing the generation of thrombin by a fluorescent probe. Instruments are small, lightweight and portable, and studies have confirmed that patients can easily and accurately perform a fingerstick and obtain a PT-INR measurement from a sample of their own blood. Most importantly, the accuracy and precision of these instruments are comparable with results from standard plasma PT determinations.^2- 4 The major limitations of these instruments include their tendency to underestimate high INRs and overestimate low INRs, the low thromboplastin sensitivity in some instruments and the inability to calculate a mean normal PT.^4- 8