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高血压治疗新指南:并非越低越好

更新时间:2014-1-21 21:34:50 来源:华尔街日报中文网 作者:佚名

New Guidelines Say Lower Blood Pressure Not Always Better
高血压治疗新指南:并非越低越好

New treatment guidelines for high blood pressure take a step back from the long-standing position that lower is always better when managing hypertension, easing the target range for people age 60 and over.

The recommendations from an expert panel say doctors should prescribe drugs to control blood pressure to these older patients whose levels are 150/90 or higher. The previous threshold for beginning treatment was 140/90.

The guidelines also raise the level to begin treatment to 140/90 for people between ages 20 and 59 who have diabetes or kidney disease. The target for those patients was previously 130/80.

For all other adults, 140/90 remains the trigger to consider taking drugs to lower the numbers.

The recommendations, being published online Wednesday by the Journal of the American Medical Association, come on the heels of new cholesterol guidelines released last month that also backed away from an aggressive lower-is-better stance that long had guided treatment policy.

But at the same time, the cholesterol recommendations lowered the risk threshold for starting treatment with cholesterol-lowering drugs called statins and increased the number of people considered candidates for the medicines.

In both cases, the pullback reflects a lack of persuasive evidence from rigorous clinical trials that meeting the specific goals significantly reduced the risk of death, heart attacks and strokes. Experts also were concerned that any marginal benefits from achieving aggressive targets would be offset by side effects from the drugs or unnecessary use of unproven treatments.

But the new recommendations--especially raising the target to 150 for older people--drew concern in an editorial accompanying their publication in JAMA. Eric Peterson, a cardiologist at Duke Clinical Research Institute in Durham, N.C., and two other experts noted that one major study linked a five-year lowering of the top number to 143 from 155 resulted in a 32% reduction in heart attacks and other cardiovascular events.

'Whether this change [to the higher target] will have adverse consequences for population health is unclear,' they wrote.

About 78 million Americans are diagnosed with high blood pressure, according to the American Heart Association, about half of whom have it controlled with medicine to levels below 140/90. The condition becomes more prevalent as people age. High blood pressure is a key risk factor for heart attacks, strokes, diabetes and kidney disease and keeping it under control is a mainstay of prevention efforts for those conditions.

Optimal blood pressure has long been regarded as below 120/80 and for natural or untreated levels, that is still the case, said Paul James, a family medicine doctor at University of Iowa Hospitals and Clinics and lead author of the new recommendations. 'People with a blood pressure of 120 have lower health risks than people with 130 or 140,' he said. But there isn't a clear association between drug treatment and health benefits, he added.

The first-line strategy for controlling blood pressure is healthy diet and exercise habits and can work for many patients. The new guidelines address only when intervention with drugs should begin.

Richard Krasuski, a cardiologist at the Cleveland Clinic, said the recommendations would give physicians and older patients more flexibility in managing hypertension. 'If anything, 150 rather than 140 will make it a little easier for the clinician and the patient,' he said.

Many older patients take two or three pills to control their blood pressure on top of other drugs to manage other illnesses, and the resulting side effects can cause people to stop taking the medicines.

'In some cases, we might have become overzealous' with the lower-is-better idea, Dr. Krasuski said. 'When you start pushing those therapies up, people start feeling worse and the data suggest they don't do better clinically.' And if they go off the drugs, they lose the benefit entirely.

The guidelines say four long-established classes of blood-pressure medicines--thiazide diuretics, calcium channel blockers, ACE inhibitors and angiotensin receptor blockers, or ARBs--all are appropriate for starting patients on medical therapy. The previous guidelines, published in 2003, recommended doctors start patients on diuretics.

In another difference from the previous guidelines, the expert panel didn't make any mention of 'pre-hypertension,' a category between 120/80 and 140/90 for which the earlier advice suggested medication could be considered. But clinical trials don't show a benefit from treating such patients.

The recommendations were based only on data from randomized clinical trials, considered the gold standard in guiding the use of drugs. But despite decades of research and hundreds of thousands of patients who have participated in trials of blood-pressure drugs, convincing data that links treatment to prevention of major events is limited.

The panel rated the evidence behind each recommendation, and only two of 11 were rated A--reflecting high confidence in the data. Six of the recommendations were rated E, meaning expert opinion--the weakest evidence.

The recommendations were developed by a group called the Eighth Joint National Committee on Prevention, Detection Evaluation and Treatment of High Blood Pressure.

针对高血压的新治疗指南从认为血压低些肯定更好的长期立场上后退一步,放宽了年龄在60岁及以上者的目标血压范围。

一个专家小组的建议说,对于血压在150/90及以上的老年患者,医生应当开药控制血压。此前开始治疗的最低界限为140/90。

相关建议还将20至59岁的糖尿病患者开始治疗的血压下限提高至140/90。此前针对这类患者的门槛是130/80。

所有其他成年人应当服药降压的门槛仍然是140/90。

上述建议今年1月1日发表在《美国医学会杂志》(Journal of the American Medical Association),在此之前,上个月刚刚发布了新胆固醇指南,也较此前长期治疗方针指导意见所持的越低越好的立场有所缓和。

但与此同时,胆固醇指南降低了开始使用名为他汀类药物的降胆固醇药进行治疗的风险门槛,从而增加了被认为应当接受这种药物治疗的人数。

在这两种情况下,标准放宽都反映出严格的临床试验中缺乏有说服力的证据,表明达到特定目标能够大大降低死亡、心脏病发作和中风的风险。专家们还担心,实现过高目标带来的些微好处会被药物或不必要地使用未经验证的治疗方法造成的副作用所抵消。

但新的指导意见——尤其是将老年人的治疗门槛定在150——引发了与之发表在同一期《美国医学会杂志》的一篇社论文章的担忧。北卡罗来纳州德罕的杜克大学临床实验中心(Duke Clinical Research Institute)心脏病学家彼得森(Eric Peterson)和另外两名专家指出,一项重大研究显示,在五年的时间内将收缩压从155降到143,导致心脏病和其他心血管疾病发作减少了32%。

他们写道,(上调血压治疗门槛)这一变化是否会对人们的健康产生不利影响尚不清楚。

美国心脏协会(American Heart Association)的数据显示,大约7,800万美国人被诊断出患有高血压,其中半数左右通过药物将血压控制在140/90以下。随着人们年龄渐长,高血压也越来越普遍。高血压是心脏病、中风、糖尿病和肾病的关键风险因素,控制血压是预防这些病症的主要措施。

爱荷华大学医院与医学中心(University of Iowa Hospitals and Clinics)的家庭医学医生、上述新血压推荐指标的主要作者詹姆斯(Paul James)说,一直以来,理想血压被认为是120/80以下,而对于自然或未经治疗的水平而言,这仍然是理想状态。他说,血压为120的人比血压为130或140的人健康风险更低,但药物治疗和健康益处之间并没有明确的关联。

控制血压的首要策略是健康饮食和锻炼习惯,这对很多患者都有效。新的指导意见只是提出了应当开始药物干预的时机。

克里夫兰诊所(Cleveland Clinic)的心脏病学家克拉苏斯基(Richard Krasuski)说,上述指导意见会让医师和老年患者在控制高血压方面更具灵活性。他说,要说有什么意义的话,150而不是140会让临床医生和患者更轻松一些。

很多老年患者除了吃药控制其他疾病之外还要吃两到三片药控制血压,由此带来的副作用可能会导致人们停止服药。

克拉苏斯基说,在一些情况下,我们可能对“越低越好”的概念过于热心了。他说,当你开始强力推行这些治疗时,人们会开始感觉更糟,数据显示在临床上并没有产生更好的效果。而一旦停药,就会彻底失去药物带来的好处。

上述治疗指南说,四类面世已久的血压药物(?帝类利尿药、钙通道阻滞药、血管紧张素转换?抑制剂和血管紧张素受体阻滞剂)在病人开始进行药物治疗时都是适合的。2003年发布的原治疗指南推荐医生在开始应用药物时使用利尿剂。

还有一个与以前治疗指南的不同之处是,专家小组没有提及“高血压前期”,这是指血压在120/80和140/90之间的水平,此前的指南建议在这一阶段可以考虑应用药物。但临床试验没有显示对这类患者进行治疗有好处。

上述治疗指南仅仅基于来自随机临床试验的数据,这被认为是指导用药的黄金标准。但尽管进行了数十年的研究,有数十万名患者参与了降压药物的试验,能够证明药物治疗与预防重大病症存在关联的有说服力的数据仍然有限。

专家小组为支持每项指导意见的证据打了分,11项指导意见中只有两项被评为A,即数据高度可信。六项指导意见被评为E,意思是专家意见——证据最为薄弱。

制定这个指导意见的组织名为第八届美国预防、检测、评估与治疗高血压全国联合委员会(Eighth Joint National Committee on Prevention, Detection Evaluation and Treatment of High Blood Pressure)。

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