Point-of-care INR coagulometers for self-management of oral anticoagulation: primary care diagnostic technology update

Abstract

Devices to measure international normalised ratio (INR) are intended for both professional use and patient self-testing to monitor oral anticoagulant therapy. INR is a standardised measurement of the prothrombin time, which is the time it takes blood to clot after addition of tissue factor. Point-of-care (POC) INR testing within primary care settings eliminates delays in waiting for the result of prothrombin time measurement to be processed by the hospital laboratory, and the subsequent delay in adjustment of anti-coagulation dosing. It also avoids the need to attend hospital anticoagulation clinics. ### Clinical Question In patients who require long-term anticoagulation treatment, how accurate and effective is self-management using a home monitoring device for INR, compared to standard practice? The POC devices use electrochemical methods or function by drawing a precise amount of blood into a micro-channel and detect clot formation when the blood movement decreases below a predetermined rate. Currently there are three coagulometers on the market which are suitable for self-testing as they use capillary whole blood obtained from a finger prick. The measuring ranges of these devices vary slightly: INR of 0.6 to 8.0 for CoaguChek® XS (Roche Diagnostics), 0.8 to 8.0 for INRatio® (Hemosense), and 0.8 to 9.9 for ProTime®/ProTime 3 (International Technidyne Corporation). The sample volume required is very small (15–30 µL) with few user dependent steps. The results are typically available in less than 5 minutes.1 Patients requiring long-term anticoagulation therapy, for atrial fibrillation, venous thromboembolism, prosthetic heart valves, or myocardial infarction and a number of pro-thrombotic conditions. Oral anticoagulation …