Oral Anticoagulation in Very Elderly Patients with Atrial Fibrillation - A Nationwide Cohort Study
Background—Stroke prevention with oral anticoagulants (OACs) is the cornerstone for the management of atrial fibrillation (AF). However, data about the use of OACs among patients aged ≥90 years are limited. We aimed to investigate the risk of ischemic stroke and intracranial hemorrhage (ICH), and the net clinical benefit (NCB) of OAC treatment for very elderly AF patients (≥90 years).
Methods—This study used the "National Health Insurance Research Database" in Taiwan. Risks of ischemic stroke and ICH were compared between 11,064 AF and 14,658 non-AF patients aged ≥90 years without antithrombotic therapy from year 1996 to 2011. AF patients (n=15,756) were divided into 3 groups (no treatment, anti-platelet agents and warfarin), and the risks of stroke and ICH were analyzed. The risks of ischemic stroke and ICH were further compared between patients treated with warfarin and non-vitamin K antagonist oral anticoagulants (NOACs) from year 2012 to 2015 when NOACs were available in Taiwan.
Results—Compared to non-AF patients, AF patients had an increased risk of ischemic stroke (event number/patient number; incidence = 742/11,064; 5.75%/year versus 1,399/14,658; 3.00%/year; hazard ratio [HR] 1.93, 95% confidence interval [CI] 1.74-2.14) and similar risk of ICH (131/11,064; 0.97%/year versus 206/14,658; 0.54%/year; HR 0.85, 95%CI 0.66-1.09) in competing risk analysis for mortality. Among AF patients, warfarin use was associated with a lower stroke risk (39/617; 3.83%/year versus 742/11,064; 5.75%/year; HR 0.69, 95%CI 0.49-0.96 in a competing risk model), with no difference in ICH risk compared to non-treatment. When compared to no antithrombotic therapy or antiplatelet drugs, warfarin was associated with a positive NCB. These findings persisted in propensity matched analyses. Compared to warfarin, NOACs were associated with a lower risk of ICH (4/978; 0.42%/year versus 19/768; 1.63%/year; HR 0.32, 95%CI 0.10-0.97 in a competing risk model), with no difference in risk of ischemic stroke.
Conclusions—Among AF patients age ≥90 years, warfarin was associated with a lower risk of ischemic stroke and positive NCB. Compared to warfarin, NOACs were associated with a lower risk of ICH. Thus, OACs may still be considered as thromboprophylaxis for elderly patients with NOACs being as the more favorable choice.
- Received September 18, 2017.
- Revision received February 6, 2018.
- Accepted February 20, 2018.