Self management of oral anticoagulant therapy after heart valve replacement.

Abstract

Patients with mechanical heart valves require lifelong oral anticoagulant treatment which entails frequent blood sampling and dosage adjustment. The purpose of this study was to investigate the feasibility of letting heart valve operated patients manage blood specimen analysis and dosage adjustment themselves. A total of 21 patients were enrolled in the study and followed for at least 9 months postoperatively. Immediately after the heart valve operation they were trained in operating a CoaguChek international normal ratio (INR) monitor to analyze capillary whole blood samples. Subsequently training in dosage adjustment was accomplished and all patients were considered fully capable of self management after 30 weeks. In the training period, parallel laboratory INR measurements were made at 3-4 week intervals for reference. A control group of 20 patients was matched, respectively, to the study group. The INR target range was 2.0-3.0. Out of the 21 study patients 19 continued self management beyond 9 months. The median INR value obtained with the monitor was within therapeutic target range for all study patients and only 15 out of 20 control patients were within this range. The mean systematic deviation between laboratory and CoaguChek INR was 7.8% but each patient had a constant characteristic deviation from -11 to +21%. The study patients were within therapeutic target range 77% of the time compared with 53% for the control patients. Self management of oral anticoagulation is feasible for selected patients and constitutes a significant service improvement compared with conventional management. The CoaguChek monitor seems sufficiently accurate and reliable for self testing and the treatment quality is comparable or even better than conventional management. Assessment of the rate of bleeding and thrombo-embolic events shall be settled in studies comprising larger number of patients.