Risks of oral anticoagulant therapy with increasing age.

Background: Oral anticoagulation in the elderly is a dilemma. Although many elderly patients have strict indications for treatment with coumarin derivatives, the tendency toward an increased bleeding risk with age is a matter of concern. We investigated the risk of hemorrhage and thromboembolism according to age in patients who were treated with oral anticoagulants in the routine setting of an anticoagulation clinic.

Methods: All patients of the Leiden Anticoagulation Clinic (Leiden, the Netherlands) who were treated because of mechanical heart valve prostheses (target, international normalized ratio [INR] of 3.5), atrial fibrillation (target, INR of 3.0), or after a myocardial infarction (target, INR of 3.0) between 1994 and 1998 were included in the study and grouped by age at the start of follow-up. We calculated incidence rates of major hemorrhage and thromboembolism per age group.

Results: We included 4202 patients: 842 patients younger than 60 years; 1200 patients aged between 60 and 70 years; 1464 patients aged between 71 and 80 years; and 696 patients older than 80 years. The incidence rate of major hemorrhage rose gradually with age from 1.5 per 100 patient-years for patients younger than 60 years to 4.2 per 100 patient-years for patients older than 80 years, yielding a hazard ratio of 2.7 (95% confidence interval, 1.7-4.4). The incidence rate of major thromboembolism rose from 1.0 per 100 patient-years for patients younger than 60 years to 2.4 per 100 patient-years for patients older than 80 years (hazard ratio, 2.2; 95% confidence interval, 1.2-4.2).

Conclusions: The incidence of both bleeding and thromboembolic events increases sharply with advanced age. Because higher thromboembolic risk with age often makes it unfeasible to withhold oral anticoagulation from elderly patients, future studies should focus on ways to lower the bleeding risk.