Summary
Oral anticoagulant therapy requires frequent laboratory controls of its intensity
to assure therapeutic efficacy and to prevent potentially life threatening adverse
events. It is generally assumed, that increasing the frequency of testing would lead
to a better control of anticoagulation. We tested this hypothesis in a prospective
controlled trial comparing weekly self-testing and self-dosing (self management) with
the standard-management of these patients in an anticoagulation clinic. Only patients
with stable anticoagulation were included into the study. We recorded 2733 weekly
determinations of the intensity of anticoagulation (INR) in 49 patients on self-testing
and self-dosing and 539 determinations of the INR in 53 patients on standard-management.
Two intensities of anticoagulation were used in each group: a target INR of 3.5 for
patients with artificial heart valves (target range: 2.5–4.5) and a target INR 2.5
(target range: 2.0–3.0) for patients with atrial fibrillation or venous thromboembolism.
The deviation from the target INR, the fraction of INR determinations within the preset
therapeutic range and the difference between the target INR and the actually achieved
mean INR were the three major endpoints of the study. The mean deviation from the
target INR was smaller in the groups of patients on self–management compared to the
patients on standard-management. Individual deviations were significantly (p <0.0001)
dependent on the type of management in interaction with the treatment intensity in
a general linear model. Patients on weekly self-testing and self-dosing had more INR
values within the therapeutic range than patients on standard-management (86.2% vs.
80.1% at INR range 2.5–4.5; 82.2 vs. 68.9 at INR range 2.0–3.0). The achieved mean
INR was almost identical with the target INR in the patients on self-management but
was significantly (p <0.005) below the target INR in the high intensity anticoagulation
group on standard-management (target INR:3.5; achieved mean INR: 3.19; CI 0.95: 3.05–3.34).
Our data show, that weekly self-testing and self-dosing leads to a better control
of anticoagulation than standard treatment in an anticoagulation clinic.
The technical equipment used for self testing in this study was provided by Roche
Diagnostics, Austria
Key words
Oral anticoagulation - artificial heart valves - venous thrombosis - self-management
