CHICAGO (EGMN) – The Framingham Heart Study risk algorithm fails to identify a significant number of individuals at high risk of coronary heart disease, and its accuracy could be improved significantly by integrating coronary calcium scoring, according to a new study from the Netherlands.

“Coronary calcium scoring, detected by CT, is a promising way to improve cardiovascular risk prediction. Population-based studies have shown that the calcium score is a strong predictor of coronary events,” said Rozemarijn Vliegenthart Proença, Ph.D., of University Medical Center Groningen (the Netherlands).

This 7-year-long study of 2,038 patients, conducted at the medical center, is supported by outcomes data demonstrating that nearly two-thirds of patients who would be classified as intermediate risk should actually be reclassified as either high or low risk. The data were reported at the annual meeting of the Radiological Society of North America.

The study investigators questioned whether adding the calcium score to known cardiovascular risk factors would actually improve risk classification in the population. It was embedded into the population-based Rotterdam Study, and 2,038 individuals aged 55-85 years were invited to participate.

“We assessed as clinical outcome coronary heart disease comprising nonfatal myocardial infarction, [coronary heart disease] mortality, coronary artery bypass grafting, and percutaneous coronary interventions,” Dr. Vliegenthart Proença said.

Investigators created two prediction models: one with variables of the Framingham risk score, fitted to this patient population, and the other including the calcium score. Risk estimates for coronary events were extrapolated to 10 years, the common time horizon for predicting cardiovascular risk.

“Then we calculated reclassification percentages to assess what the actual effect is of adding the calcium score to risk factors. Finally we compared the predicted risk, in the different categories, to the actually observed risk,” Dr. Vliegenthart Proença said.

Patients had a mean age of 70 years, and 1,171 (57%) were women. During the course of the study, 84 men and 45 women had a coronary event.

An elevated calcium score corresponded to significantly increased risk of events. Men with a calcium score over 400 had a sevenfold increased risk, compared with men who had a calcium score of 0-10. “When we adjusted for cardiovascular risk factors, these relative risks did not materially change,” Dr. Vliegenthart Proença said.

The strong association between the amount of coronary calcification and the risk of coronary heart disease was evident in the women’s cohort as well.

When the calcium score was included with the Framingham risk score, almost 30% migrated to different risk categories. Reclassification was most prominent in the intermediate Framingham risk category, where nearly two-thirds of men and women were reclassified as either lower or higher risk.

According to Dr. Vliegenthart Proença, this was one of the study’s strengths.

“Reclassification was based on the actual events. The observed risk in the different categories were calculated on the basis of our risk model, our prediction model, and on the basis of the actual events occurring in the different risk categories.”

An audience member questioned whether the Netherlands has used this data to change treatment recommendations.

“Actually, that’s work in progress. At this moment there is no screening for coronary calcium in the Dutch population,” Dr. Vliegenthart Proença said.

Session moderator Dr. Frank John Rybicki III of Harvard Medical School, Boston, agreed.

“This was an important study because it used actual patient outcomes with a follow-up of almost 7 years to then reclassify risk, integrating calcium score into the traditional methods of risk, which is the Framingham model. And it showed with outcomes that there is a positive influence integrating calcium with those more traditional risk factors. It pretty specifically shows that integration of the calcium score has a very high chance of being beneficial in determining one’s overall risk.”

In a separate presentation, Dr. Vliegenthart Proença argued for noninvasive cardiac imaging of asymptomatic patients with peripheral arterial disease. A randomized, controlled trial of 231 such patients at her institution found that one in five were indicated for coronary revascularization.

Dr. Rybicki did not find this surprising. “A fifth of patients with peripheral arterial disease are also going to have significant coronary disease. We expect that. The main finding that 20% of those patients actually have severe coronary disease is interesting and important to demonstrate, but not particularly surprising.”

The study was sponsored by University Medical Center Groningen.

Dr. Vliegenthart Proença did not disclose any financial conflicts of interest.

Dr. William E. Golden, professor of medicine and public health at the University of Arkansas, Little Rock, commented on the findings in an interview. “The Framingham risk score is based on observations of thousands of patients over decades. It is particularly useful in determining primary prevention interventions for middle-aged patients.

This study is provocative but appears to include an older group of individuals who would be at higher risk for cardiac events based on their age alone. It may be premature to extrapolate these findings to younger patients.”

Dr. Golden, who was not involved in the research, said he had no conflicts of interest with regard to this topic.

Copyright (c) 2009 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

芝加哥(EGMN) —— 一项在荷兰开展的最新研究表明，Framingham心脏研究风险计算公式并不能识别出大量冠心病高危人群，若结合冠状动脉钙化评分则可显著提高其预测的准确性。 

荷兰格罗宁根大学医学中心的Rozemarijn Vliegenthart Proença博士说：“基于CT扫描的冠状动脉钙化评分有望成为提高心血管风险预测准确性的重要途径之一。基于人群的研究已经证实，钙化评分是冠脉事件的强预测因子之一。” 

这项长达7年的研究共纳入了2,038例患者，在荷兰格罗宁根大学医学中心开展，结局指标的分析结果表明，几乎2/3的被归为中等风险组的患者实际上应重新分类，归为高风险或低风险组。研究者在北美放射学会2009年年会上报告了该研究结果。 

研究者们质疑在已知心血管危险因素的基础上增加钙化评分是否真正有助于人群的风险分类。这项在荷兰鹿特丹开展的基于人群的研究便是为了解答这一问题，2,038例年龄介于55~85岁的受试者应邀参与该研究。 

Vliegenthart Proença博士解释到：“我们对冠心病的临床转归进行了评价，包括非致命性心肌梗死、冠心病病死率、冠状动脉旁路移植术以及经皮冠状动脉介入治疗。” 

研究者确立了两个预测模型：一个采用的是Framingham风险评分的参数并根据受试人群对模型进行拟合；另一个则纳入了钙化评分。将冠脉事件的风险估值外推到10年以后，这也是预测心血管风险的常用时间跨度。 

Vliegenthart Proença博士说：“然后，我们计算了需要重新分类的患者百分比，以评价在已知危险因素基础上增加钙化评分的实际意义。最后我们比较了各风险组的预测风险与实际观察到的风险之间的差异。” 

患者的平均年龄为70岁，其中1,171例(57%)为女性。试验期间，共有84例男性和45例女性发生冠脉事件。 

钙化评分升高与冠脉事件发生风险显著增加相关。与钙化评分介于0~10分的男性患者相比，钙化评分>400分的男性患者风险增加了7倍。Vliegenthart Proença博士指出，“对心血管危险因素进行校正后，这种相对风险也无实质性的改变。” 

在女性患者队列中，冠状动脉钙化程度与冠心病风险之间的强相关性也非常明显。 

如果将钙化评分与Framingham风险评分综合使用，近30%的患者都会被重新归到另一个风险组。在Framingham中等风险组中重新分类的发生率最高，几乎2/3的男性或女性患者都被重新归为高风险或低风险组。 

Vliegenthart Proença博士指出，这是该研究的重大发现之一。 

“重新分类是基于实际发生的冠脉事件。基于我们确立的风险模型、预测模型以及各风险组实际发生的事件来计算各风险组实际观察到的风险。” 

一名听众提出疑问，荷兰是否会基于该研究数据更改相关的治疗建议。 

Vliegenthart Proença博士回答：“事实上，我们正在开展相关工作。目前还没有任何针对荷兰人群冠状动脉钙化的筛查计划。” 

作为会议主持人，美国哈佛医学院的Frank John Rybicki III博士表示赞同。 

“这是一项有着重要意义的研究，因其基于近7年的随访数据，根据患者的实际转归重新进行风险分类，综合运用了钙化评分与传统的风险预测方法，即Framingham模型。结果显示，将钙化评分与传统的风险因素相结合有助于提高风险预测的准确性。尤其值得注意的是，综合运用钙化评分对于确定患者的总体风险可能非常有用。” 

在另一次报告中，Vliegenthart Proença博士主张对无症状性周围血管疾病患者采用无创性心脏成像检查。一项随机对照试验纳入了231例来自她所在机构的无症状性周围血管疾病患者，结果发现，其中1/5的患者都有行冠状动脉血运重建术的指征。 

Rybicki博士对此并不感到意外。“我们预计1/5的周围血管疾病患者还将出现明显的冠脉疾病。该试验的主要发现是20%的受试者实际上患有严重的冠脉疾病，这一结果值得关注，也有着重要的意义，但并不令人惊讶。” 

该试验由荷兰格罗宁根大学医学中心资助。 

Vliegenthart Proença博士声明无经济利益冲突。 

美国阿肯色大学的医学与公共卫生学教授William E. Golden博士在采访中对上述研究结果发表了评论，“Framingham风险评分法是基于几十年来对数千例患者的观察结果而制定的，它在确定中年患者的一级预防干预措施方面起着极其重要的作用。” 

这项研究的确值得关注，但该研究只纳入了老年患者，单凭年龄来讲这类患者发生心脏事件的风险本身就比较高。现在就将该研究结果外推至相对年轻的患者尚为时过早。 

Golden博士并未参与这项研究，声明无相关利益冲突。 

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