Post-stroke anticoagulation therapy may be more likely to result in net clinical benefit in older patients with atrial fibrillation (AF) and non-sex related risk factors, according to a study recently published in JAMA Cardiology.
This retrospective population-based cohort study included 16,351 adults with a new AF diagnosis who were between the ages of 66 and 74 (median age, 70) years, of whom 51.1% are men. The study period ranged from April 2007 to March 2017.
All those included in the study were diagnosed with AF in Ontario, Canada, and received health coverage through the province’s insurance plan. Anyone with prior anticoagulation therapy, heart failure, valvular heart disease, hypertension, stroke, diabetes, or vascular disease, or who lived in a long-term care facility, was excluded.
Hospitalization for stroke was the primary outcome. To estimate the 1-year stroke incidence among those not treated with anticoagulation therapy, the study researchers used a cumulative incidence function. The association between participant characteristics and stroke incidence was assessed using Fine-Gray regression, which allowed for a model of estimated 1-year stroke risk with age. The analysis treated death as a competing risk.
Among the study population, 38.6% (n=6314) began anticoagulation therapy in the follow-up period. Among those who did not begin anticoagulation therapy, the rate of death without stroke was 8.1% (95% CI, 7.7% to 8.5%), and the 1-year incidence of stroke was 1.1% (95% CI, 1.0% to 1.3%). No significant association between stroke and sex was found.
However, an increase in 1-year stroke risk was observed to correlate with aging from 66 years (0.7%; 95% CI, 0.5% to 0.9%) to 74 years (1.7%; 95% CI, 1.3% to 2.1%), with a subdistribution hazard ratio of 1.12 per year (95% CI, 1.06-1.18; P <.001).
Limitations to these findings include potential residual confounding, a lack of data on factors such as race and socioeconomic health determinants, a potential immortal time bias, the possibility of including individuals without AF, and a potential misestimation of stroke risk.
The study researchers concluded that there is “a greater likelihood of benefit from anticoagulation therapy among older patients,” and that “the estimation of stroke risk in patients with AF may be enhanced by models that treat age as a continuous rather than a categorical variable.”
Disclosures: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Abdel-Qadir H, Singh SM, Pang A, et al. Evaluation of the risk of stroke without anticoagulation therapy in men and women with atrial fibrillation aged 66 to 74 years without other CHA2DS2-VASc factors. JAMA Cardiol. Published online May 19, 2021. doi:10.1001/jamacardio.2021.1232