Importance There are limited clinical trial data and discrepant recommendations regarding use of anticoagulation therapy in patients with atrial fibrillation (AF) aged 65 to 74 years without other stroke risk factors.

Objectives To evaluate the risk of stroke without anticoagulation therapy in men and women with AF aged 66 to 74 years without other CHA₂DS₂-VASc (congestive heart failure, hypertension, age ≥75 years, diabetes, stroke, vascular disease, age 65-74 years, female sex) risk factors and examine the association of stroke incidence with patient age.

Design, Setting, and Participants A population-based retrospective cohort study was conducted using linked administrative databases. The population included 16 351 individuals aged 66 to 74 years who were newly diagnosed with AF in Ontario, Canada, between April 1, 2007, and March 31, 2017. Exclusion criteria included long-term care residence, prior anticoagulation therapy, valvular disease, heart failure, hypertension, diabetes, stroke, and vascular disease. The cumulative incidence function was used to estimate the 1-year incidence of stroke in patients who did not receive anticoagulation therapy. Fine-Gray regression was used to study the association of patient characteristics with stroke incidence and derive estimates of stroke risk at each age. Death was treated as a competing risk and patients were censored if they initiated anticoagulation therapy. Inverse probability of censoring weights was used to account for patient censoring. Data analysis was performed from May 26, 2019, to December 9, 2020.

Exposures Atrial fibrillation and age.

Main Outcomes and Measures Hospitalizations for stroke.

Results Of the 16 351 individuals with AF (median [interquartile range] age, 70 [68-72] years), 8352 (51.1%) were men; 6314 individuals (38.6%) started anticoagulation therapy during follow-up. The overall 1-year stroke incidence among patients who did not receive anticoagulation therapy was 1.1% (95% CI, 1.0%-1.3%) and the incidence of death without stroke was 8.1% (95% CI, 7.7%-8.5%). The incidence of stroke was not significantly associated with sex. The estimated 1-year stroke risk increased with patient age from 66 years (0.7%; 95% CI, 0.5%-0.9%) to 74 years (1.7%; 95% CI, 1.3%-2.1%).

Conclusions and Relevance The risk of stroke more than doubled in this study as men and women with AF but no other CHA₂DS₂-VASc risk factors aged from 66 to 74 years. These data suggest that anticoagulation therapy is more likely to benefit older individuals within this group of patients, whereas younger individuals are less likely to gain net clinical benefit from anticoagulation therapy.

重要性 对于年龄在 65 至 74 岁且无其他卒中危险因素的心房颤动 (AF) 患者使用抗凝治疗的临床试验数据有限且建议不一致。

目的 评估 66 至 74 岁且无其他 CHA ₂ DS ₂ -VASc（充血性心力衰竭、高血压、≥75 岁、糖尿病、中风、血管疾病、65 岁-74 岁，女性）危险因素，并检查中风发病率与患者年龄的关系。

设计、设置和参与者 使用链接的管理数据库进行了一项基于人群的回顾性队列研究。该人群包括 2007 年 4 月 1 日至 2017 年 3 月 31 日期间在加拿大安大略省新诊断为 AF 的 16 351 名年龄在 66 至 74 岁之间的个体。排除标准包括长期护理居住、先前的抗凝治疗、瓣膜疾病、心力衰竭、高血压、糖尿病、中风和血管疾​​病。累积发病率函数用于估计未接受抗凝治疗患者的 1 年卒中发病率。精细灰色回归用于研究患者特征与卒中发病率的关联，并得出每个年龄的卒中风险估计值。死亡被视为一种竞争风险，如果患者开始抗凝治疗，他们将被审查。审查权重的逆概率用于解释患者审查。数据分析时间为 2019 年 5 月 26 日至 2020 年 12 月 9 日。

暴露 心房颤动和年龄。

主要结果和措施 中风住院率。

结果 在 16 351 名 AF 患者中（中位 [四分位距] 年龄，70 [68-72] 岁），男性 8352 人（51.1%）；6314 人（38.6%）在随访期间开始抗凝治疗。未接受抗凝治疗的患者总体 1 年卒中发生率为 1.1%（95% CI，1.0%-1.3%），非卒中死亡发生率为 8.1%（95% CI，7.7%-8.5%） . 中风的发生率与性别无显着相关性。随着患者年龄的增长，估计的 1 年卒中风险从 66 岁（0.7%；95% CI，0.5%-0.9%）增加到 74 岁（1.7%；95% CI，1.3%-2.1%）。

结论和相关性在这项研究中 ，66 至 74 岁的 AF 但没有其他 CHA ₂ DS ₂ -VASc 危险因素的男性和女性中风的风险增加了一倍以上。这些数据表明，在这组患者中，抗凝治疗更有可能使老年人受益，而年轻个体从抗凝治疗中获得净临床益处的可能性较小。