Vitamin K Antagonist Treatment in Elderly Patients
What is the age-associated risk of bleeding and thrombosis in patients ≥70 years old who are treated with vitamin K antagonists (VKAs)?
The authors performed a matched cohort study of patients at a single thrombosis service treated with VKA between January 21, 2009 and June 30, 2012. The majority of patients (63.8-71.7% of each age cohort) were treated for stroke prevention in atrial fibrillation. Patients were matched 1:1:1 by decade (70-79, 80-89, 90-99 years) and duration of treatment. The primary outcome was a composite of clinically relevant nonmajor and major bleeding. Secondary outcome was thrombosis and quality of VKA control (Rosendaal time in the therapeutic range [TTR]) for a target international normalized ratio (INR) range of 2.0-3.5 or 2.5-4.0 given the predominate use of acenocoumarol.
Over 6,419 observation-years, 713/3,313 patients had 1,050 bleeding events. Bleeding risk was mildly increased in patients in their 90s versus 70-79 years (18.1 vs. 14.8 events/100 patient-years; hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.05-1.50), but not in patients ages 80-89 years (HR, 1.07; 95% CI, 0.89-1.27). The increased risk of bleeding was predominately in men (HR, 1.71; 95% CI, 1.30-2.24 for ≥90 vs. 70-79 years), but not seen in women (HR, 1.11; 95% CI, 0.86-1.43 for ≥90 vs. 70-79 years). Thrombotic events were experienced in 85/3,313 (2.6%) patients. Thrombotic risk was higher for patients in their 90s (HR, 2.14; 95% CI, 1.22-3.75) and 80s (HR, 1.75; 95% CI, 1.002-3.05) versus patients in their 70s. TTR declined from 73.5% to 66.4% between patients in their 70s and 90s (p < 0.001).
The authors concluded that elderly patients, especially women, receiving VKA therapy have minimally elevated bleeding risk, but significantly increased thrombotic risk as they age.
This single-center analysis from The Netherlands challenges a commonly held misconception that elderly patients are at prohibitively high bleeding risk for anticoagulation therapy. While the target INR ranges and VKA agent used in this center’s patients do not directly match with those commonly used in North America, the overall message is still important and relevant. With high-quality anticoagulation control, a patient’s age alone should not prohibit life-saving anticoagulation therapy. In fact, age is one of the strongest predictors of stroke risk in atrial fibrillation. This is especially true for women who exhibited no increased risk of bleeding with increased age, but are known to be at higher thrombotic risk than men with atrial fibrillation. Clinicians should make every effort to provide adequate anticoagulation therapy for all patients at risk of thrombotic disorders, especially elderly patients with atrial fibrillation.
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