新风险评分模型对AF卒中的预测效果佳

《美国心脏协会杂志》在线发表的一篇报告显示，基于AF抗凝和危险因素(ATRIA)研究队列的数据，新的卒中风险评分模型的效能优于目前主要临床指南推荐的模型J. Am. Heart Assoc. 2013; 2013[doi: 10.1161/?JAHA.113.000250])。

研究者首先在一项推导研究中建立了ATRIA模型，然后在另一项验证研究中证实其准确性。结果显示，该ATRIA评分模型识别的卒中低危患者比例为46%，显著高于目前广泛使用的其他危险评分模型识别的比例。这将使临床医生考虑对近半数AF患者放弃抗凝治疗。这一新模型在计算一级预防患者的卒中风险方面特别有用，一级预防患者是卒中风险最不确定且最迫切需要进行个体化抗凝决策的大型患者人群。此外，该模型特别有助于预测重度卒中，这是医生最想避免的卒中类型。

主要研究者、麻省总医院临床流行病科的Daniel E. Singer医生及其同事从多个大型健康计划数据库中查找到1996~1997年被诊断为非瓣膜性AF且随访至2003年的13,559名加州成人作为推导队列。这些受试者在华法林治疗期间的观察数据为33,497人-年，华法林停用后的观察数据为10,927人-年。该推导队列发生了685起血栓栓塞事件，包括643起缺血性卒中。研究者发现，患者年龄和既往卒中史是对未来卒中风险影响最大的两个因素。

研究者从这些数据中发现了8个可纳入其危险评估模型的高度预测性变量：年龄、既往卒中、女性性别、糖尿病、心力衰竭、高血压、蛋白尿和终末期肾病或估计肾小球滤过率＜ml/min•1.73 m2。

该风险预测模型与现行模型的主要区别在于，前者采用了更广泛的年龄类别范围；将年龄、既往卒中及其与主要危险因素之间的相互作用加入计算中；以及将新高危因素(如女性、肾功能不全)加入计算中。

在使用ATRIA风险模型的情况下被准确归入低危或高危类别的受试者比例，高于使用其他模型得出的比例。ATRIA卒中风险评分较CHADS2卒中风险评分改善26%，这主要是通过正确将许多患者从中危类别上调至高危类别而达成的。此外，ATRIA卒中风险评分较CHA2DS2-VASc卒中风险评分改善27%，这完全是通过正确将许多患者从高危或中危类别下调至低危类别而达成的。

研究者随后在一个包含33,247例在2006~2009年间新诊断为AF的成人验证队列中证实了ATRIA卒中危险评分的准确性。这些受试者在华法林停用后的观察数据为26,263人-年，在华法林治疗期间的观察数据为25,306人-年。该验证队列发生了496起血栓栓塞事件，包括466起缺血性卒中。在验证队列中使用新的ATRIA卒中风险模型，发现低危、中危和高危类别中的患者分布情况与在推导队列观察到的非常相似。同样，ATRIA评分在卒中低危患者和高危患者分类方面的准确性也优于现有模型。

具体而言，推导队列和验证队列中均有46%的患者被ATRIA评分归入每年卒中风险＜1%的类别。这将特别有助于临床医生决定哪些患者可安全放弃抗凝治疗。同样，ATRIA评分识别重度(相对于轻度)卒中事件的准确性明显优于另外两个危险模型。这将非常有助于临床医生决定哪些患者最需要抗凝治疗。研究者表示，近期研究表明目前某些生物标志物可能是AF患者卒中风险的有效预测因素，如果证明如此，就可容易地将这些生物标志物加入ATRIA评分模型中进一步改善卒中风险评估。

该研究获美国国立衰老研究所、美国国立心肺血液研究所及麻省总医院Eliot B.和Edith C. Shoolman基金支持。Singer医生声明与拜耳等多家药企存在联系。

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By: MARY ANN MOON, Cardiology News Digital Network

A new scheme for assessing stroke risk, based on data amassed in the Anticoagulation and Risk Factors in AF, or ATRIA, cohort, performed better than the schemes currently recommended in leading clinical guidelines, according to a report published online in the Journal of the American Heart Association.

In a derivation study in which the ATRIA scheme was developed and a separate validation study in which its accuracy was confirmed, the ATRIA scores identified a substantially larger proportion of atrial fibrillation patients – 46% – as being at low risk for stroke, compared with other risk schemes currently in widespread use. This would allow clinicians to consider forgoing anticoagulant therapy in nearly half of AF patients.

The new scheme was particularly useful in calculating stroke risk in primary prevention patients, "the large group whose stroke risk is the most uncertain and where personalizing the anticoagulation decision is most pressing," said Dr. Daniel E. Singer of the clinical epidemiology unit, Massachusetts General Hospital, Boston, and his associates.

In addition, the ATRIA scores were especially good at predicting severe strokes, "the category of stroke that we are most interested in avoiding," the investigators noted.

Dr. Singer and his colleagues first used large health-plan databases to identify 13,559 California adults diagnosed as having nonvalvular AF in 1996-1997 and followed through 2003. These study subjects accounted for 33,497 person-years of observation on warfarin and 10,927 person-years of observation off warfarin.

There were 685 thromboembolic events, including 643 ischemic strokes, in this derivation cohort. Patient age and personal history of prior stroke were the two factors found to exert the greatest effect on future stroke risk.

From these data, the investigators identified eight highly predictive variables to incorporate into their risk assessment model: age, prior stroke, female sex, diabetes, heart failure, hypertension, proteinuria, and end-stage renal disease or an estimated glomerular filtration rate less than 45 mL/min per 1.73 m2.

This risk-prediction scheme differs from existing schemes primarily in that it uses a broader range of age categories; makes age, prior stroke, and their interaction the predominant risk factors to weigh into the calculation; and adds new high-risk factors such as female sex and renal dysfunction into the calculation.

When this ATRIA risk scheme was used, many more study subjects were accurately classified as low or high risk than with other schemes, the investigators said (J. Am. Heart Assoc. 2013; 2013[doi: 10.1161/?JAHA.113.000250]).

The ATRIA stroke risk score improved on the CHADS2 (congestive heart failure, hypertension, age at least 75 years, diabetes, stroke [doubled]) stroke risk score by 26%, primarily by correctly upgrading many patients from moderate-risk to high-risk categories. And it improved on the more recently identified CHA2DS2-VASc (congestive heart failure or left ventricular dysfunction, hypertension, age at least 75 years [doubled], diabetes, stroke [doubled]-vascular disease, age 65-74, sex category [female]) stroke risk score by 27%, exclusively by correctly downgrading many patients from high- or moderate-risk categories to the low-risk category.

The researchers then confirmed the accuracy of the ATRIA stroke risk scheme by testing it in a validation cohort of 33,247 adults who were newly diagnosed as having AF in 2006-2009. These study subjects accounted for 26,263 person-years off warfarin and 25,306 person-years on warfarin.

There were 496 thromboembolic events, including 466 ischemic strokes, in this validation cohort.

When the new ATRIA stroke risk scheme was used, the distribution of patients into low-, moderate-, and high-risk categories was "remarkably similar" to that in the derivation cohort. Similarly, the ATRIA scores were much more accurate than those in current standard use at determining which patients were at low risk and which were at high risk for stroke.

In particular, 46% of patients in both the derivation and validation cohorts were categorized by their ATRIA score as having a less than 1% per year risk of stroke. This designation would be extremely helpful to clinicians in deciding which patients can safely forgo anticoagulation therapy, Dr. Singer and his associates said.

Similarly, the ATRIA score was markedly better than the other two risk schemes at discriminating risk for severe, as compared with minor, stroke events. This would be very helpful to clinicians in deciding which patients are most in need of anticoagulation therapy, they said.

Recent research indicates that certain biomarkers now also appear to be promising predictors of stroke in AF patients. If this proves to be true, such biomarkers can easily be added into the ATRIA scoring scheme to further improve stroke risk assessment, the investigators added.

This study was supported by the National Institute on Aging; the National Heart, Lung, and Blood Institute; and the Eliot B. and Edith C. Shoolman Fund of Massachusetts General Hospital. Dr. Singer reported ties to Bayer Healthcare, Boehringer Ingelheim, Bristol-Myers Squibb, Daiichi Sankyo, Johnson & Johnson, and Pfizer.