USPSTF：勿对一般人群筛查颈动脉狭窄

根据美国预防服务工作组（USPSTF）7月7日在《内科学年鉴》在线发表的推荐意见，对于一般人群中没有卒中、短暂性缺血发作（TIA）、神经症状体征病史的无症状成年人，不应当筛查颈动脉狭窄。

密苏里大学的Michael L. LeFevre博士及其USPSTF的同事指出，所有筛查策略，哪怕是诸如超声之类的非侵入性筛查，都不能足够敏感地检出颈动脉狭窄。而且所有筛查策略都可能导致不必要的治疗，或者其本身可带来严重伤害（包括死亡、卒中和心肌梗死）。因此，目前“筛查无症状颈动脉狭窄的伤害超过获益”

本次发表的是对2007年推荐意见的更新，后者也认为在一般人群中筛查颈动脉狭窄是不必要的。在本次更新中，USPSTF对数年来积累的数据进行了彻底的综述和meta分析。

USPSTF共同主席LeFevre博士及其同事对近年来的相关随机对照试验、meta分析和队列研究进行了综述。他们发现，一般成年人群中的颈动脉狭窄患病率仅有0.5%~1%。最可行的颈动脉狭窄筛查方法是多普勒超声检查，但在临床实践中，即使是这种筛查也会在一般成年人群中产生大量假阳性结果，从而带来伤害。

不仅如此，没有证据表明另一种非侵入性筛查方法——颈部听诊以发现颈部杂音——能准确检出颈动脉狭窄或者带来任何益处。仅有4项研究检验这一策略，其中无一采用血管造影作为诊断金标准，仅有2项研究纳入了来自一般人群的患者。而且，即使对无症状患者的筛查发现了病变并早期进行干预，“获益程度也只是聊胜于无”。

另一方面，颈动脉内膜切除术（CEA）后30天内的卒中或死亡率在总体上约为2.4%。然而，在低通量医疗中心，这一比例可高达5%，在某些州可高达6%。与颈动脉成型及支架置入术（CAAS）相关的30天卒中或死亡率介于3.1%~3.8%。USPSTF指出，这一风险远远超过了筛查所带来的微小获益。CEA或CAAS的其他重要伤害包括心肌梗死、手术并发症、颅神经损伤、肺栓塞、肺炎和需要额外手术的局部血肿。

高质量数据的缺乏妨碍了综述和meta分析的开展。尚需要更多关于接受CEA或CAAS的患者与接受合理药物治疗的患者的结局对比数据。计划中的CREST-2（颈动脉重建内膜切除术与支架置入术对比试验2）将纳入单纯接受药物治疗的对照组，将提供有关这一问题的重要结果。

作者们补充道，USPSTF反对在一般人群中筛查颈动脉狭窄的推荐意见与美国心脏协会（AHA）、美国卒中学会（ASA）、美国心脏病学会（ACC）、美国神经外科医师协会（AANS）、美国放射学会（ACR）、美国神经放射学会（ASN）、血管外科学会（SVS）、血管医学会（SVM）以及美国家庭医师协会（AAFP）的推荐意见一致。

访问USPSTF网站可了解更多有关其推荐意见的信息。

USPSTF是一个独立组织，旨在针对具体预防保健服务提出推荐意见，是由美国医疗保健研究与质量局资助的。

人群可归因风险仅为0.7%

供职于杜伦退伍军人事务部医疗中心、杜克大学卒中中心的Goldstein医生在随刊述评中指出，USPSTF重申了其反对在一般人群中筛查无症状颈动脉狭窄的既往推荐意见，这一态度得到了现有数据的明确支持，尽管“这些筛查仍然在被广泛使用”。

患者应当了解，这类检查不太可能阻止他们发生卒中或改善他们的健康状况。与无症状CAS相关的人群可归因卒中风险仅为0.7%——这与高血压（人群可归因风险超过95%）、房颤（人群可归因风险可高达24%，具体取决于患者年龄和其他因素）、吸烟（人群可归因风险可高达14%）和高血脂（人群可归因风险为9%）等危险因素相比微不足道。

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By: MARY ANN MOON, Cardiology News Digital Network

Asymptomatic adults in the general population who have no history of stroke, transient ischemic attack, or neurologic signs or symptoms should not be screened for carotid artery stenosis, according to a U.S. Preventive Services Task Force recommendation published online July 7 in Annals of Internal Medicine.

All screening strategies, even a noninvasive one that has minimal harmful effects such as ultrasonography, are insufficiently sensitive for detecting the condition. And all of them can lead to unnecessary treatment or can themselves induce serious harms including death, stroke, and myocardial infarction. Therefore, at this time, "the harms of screening for asymptomatic carotid artery stenosis outweigh the benefits," said Dr. Michael L. LeFevre of the University of Missouri, Columbia, and his associates with the USPSTF.

The recommendation is an update of the previous one issued in 2007, which also concluded that screening the general population for carotid stenosis was unwarranted. For this update, the USPSTF performed an exhaustive review and meta-analysis of the data that have accrued since that time, which addressed advances in screening tests, risk stratification tools, both screening and treatment using carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAAS), and optimal medical therapies.

Dr. LeFevre, a cochair of USPSTF, and his colleagues reviewed recent randomized controlled trials, meta-analyses, and cohort studies of these topics. They found that the prevalence of carotid artery stenosis is only 0.5%-1% in the general population of adults. The most feasible screen for the condition is duplex ultrasonography; but in real-world practice, even this screen yields many false-positive results in such patients, and so exposes them to harm.

There also is no evidence that another noninvasive screen for carotid artery stenosis – auscultation of the neck to detect carotid bruits – is accurate or provides any benefit. Only four studies examined this strategy; none of them used angiography as a gold standard for diagnosis, and only two involved patients from the general population.

Moreover, even when screening of asymptomatic patients leads to detection and early intervention, "the magnitude of benefit is small to none." In particular, adding medications to current optimal medical management does not appear to convey any benefit, Dr. LeFevre and his associates said.

On the other side of the benefit-to-harm scale, carotid endarterectomy is associated with a 30-day rate of stroke or mortality of approximately 2.4% overall. However, the rates are as high as 5% in low-volume medical centers and 6% in certain states. The 30-day rate of stroke or mortality associated with CAAS is 3.1%-3.8%. Those risks are far too high to counterbalance the small benefit of screening, the USPSTF reviewers noted.

Other important harms after CEA or CAAS include myocardial infarction, surgical complications, cranial nerve injury, lung embolism, pneumonia, and local hematoma requiring further surgery.

The review and meta-analysis were hampered by a dearth of high-quality data. Specifically, much more data are needed comparing patient outcomes after CEA or CAAS with those after optimal medical therapy. The planned CREST-2 (Carotid Revascularization Endarterectomy vs Stenting Trial 2) will include a comparator group on medical management alone, and should provide important findings in this regard, Dr. LeFevre and his associates said.

They added that the USPSTF recommendation against screening the general population for carotid stenosis agrees with recommendations from the American Heart Association, American Stroke Association, American College of Cardiology, American Association of Neurological Surgeons, American College of Radiology, American Society of Neuroradiology, Society for Vascular Surgery, Society for Vascular Medicine, and the American Academy of Family Physicians.

More information on this recommendation – as well as recommendations for the related issues of hypertension, dyslipidemia, CHD, and diet – is available at the USPSTF website.

The USPSTF is an independent group that makes recommendations about the effectiveness of specific preventive care services and is funded by the Agency for Healthcare Research and Quality.

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Population-attributable risk only 0.7%

The available data clearly support the USPSTF’s reaffirmation of its previous recommendation against screening for asymptomatic carotid artery stenosis in the general population, yet "such screenings are offered throughout the country in health fairs and other settings," said Dr. Larry B. Goldstein.

Patients should be aware that such tests are unlikely to prevent them from having a stroke or to otherwise improve their health. The population-attributable risk for stroke related to asymptomatic CAS is only 0.7% – a figure that is dwarfed by such factors as hypertension (population-attributable risk greater than 95%), atrial fibrillation (population-attributable risk as high as 24%, depending on patient age and other factors), cigarette smoking (population-attributable risk of up to 14%), and hyperlipidemia (population-attributable risk of 9%), he noted.

Dr. Goldstein is at Duke University’s Stroke Center and Durham Veterans Affairs Medical Center in Durham, N.C. These remarks were taken from his editorial accompanying Dr. LeFevre’s report.