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首页 » 冠心病 » JAMA:B 族维生素对降低冠心病患者的死亡或主要心血管不良事件的风险没有效果

JAMA:B 族维生素对降低冠心病患者的死亡或主要心血管不良事件的风险没有效果

来源:EurekAlert!中文版 2008-08-20 09:40

据8月20日刊JAMA上的一则研究披露,一项大型的临床试验显示,冠心病患者服用B族维生素对预防死亡或心血管不良事件没有效果。

根据文章作者提供的背景资料:"观察研究证明,血液中的总同型半胱氨酸浓度与冠心病和中风的风险有关联。"血浆的总同型半胱氨酸水平可以通过口服叶酸和维生素B12 而被降低。在这一研究中,作者的目的是为了评估 叶酸加上维生素B12 的降低同型半胱氨酸的治疗对降低心血管不良事件是否有效。

Haukeland University Hospital, Bergen, Norway的Marta Ebbing, M.D.及其同僚开展了一项随机并有对照组的研究,对象是在1999-2006年期间在2家挪威医院中的3096位患者。病人被随机分配至4个小组中的某一小组,各小组成员每日分别接受一次下列某种口服药物治疗:叶酸0.8毫克加上维生素B12 0.4毫克加上维生素B6 40毫克(n=772);叶酸加上维生素B12 (n = 772);仅服用维生素B6 (n = 772);或安慰剂(n = 780)。这些病人被安排在试验开始后1个月、1年及在最后一次研究访问中进行随访,随访内容有面谈、临床检查和抽血检查。主要结果(即主要终点)的衡量有:全因死亡集成、非致命性急性心肌梗塞(即心脏病发作)、因不稳定性心绞痛而急性住院及非致命性血栓栓塞性中风。

这项研究被提前中止,因为另外一个类似的挪威研究显示了令人担心的初步结果,这些结果提示这种治疗没有益处,且病人还会因为服用B族维生素而增加癌症的风险。

文章的作者报告说:"在经过一年的治疗后,那些接受叶酸和维生素B12 的患者的血浆总同型半胱氨酸平均浓度下降了30%。在38个月时的中位时间随访时,共有422位试验参与者(占13.7%)经历了主要终点:其中219名参与者(占14.2%)接受了叶酸/维生素B12 的治疗, 而203名参与者(占13.1%)则没有接受这种治疗;有200名参与者(占13.0%)接受了维生素B6 的治疗,而222名参与者(占14.3%)则没有接受维生素B6 的治疗。"

文章的作者得出结论:"…我们没有发现叶酸加维生素B12 或维生素B6 的干预 对那些接受了强化常规治疗的稳定性冠心病患者的死亡率或主要心血管事件有任何的预防性效果。我们发现,在那些接受叶酸的治疗组中,中风发生率在数字上有所降低,而其癌症的发生率则较高,但这些观察在统计上没有显著性。我们的发现不支持用B族维生素作为冠心病患者的次级预防手段。"(生物谷Bioon.com)

生物谷推荐原始出处:

JAMA, August 20, 2008; 300: 795 - 804.

Mortality and Cardiovascular Events in Patients Treated With Homocysteine-Lowering B Vitamins After Coronary Angiography

Marta Ebbing, MD; Øyvind Bleie, MD, PhD; Per Magne Ueland, MD, PhD; Jan Erik Nordrehaug, MD, PhD; Dennis W. Nilsen, MD, PhD; Stein Emil Vollset, MD, DrPH; Helga Refsum, MD, PhD; Eva Kristine Ringdal Pedersen, MD; Ottar Nygård, MD, PhD

JAMA. 2008;300(7):795-804.

Context  Observational studies have reported associations between circulating total homocysteine concentration and risk of cardiovascular disease. Oral administration of folic acid and vitamin B12 can lower plasma total homocysteine levels.

Objective  To assess the effect of treatment with folic acid and vitamin B12 and the effect of treatment with vitamin B6 as secondary prevention in patients with coronary artery disease or aortic valve stenosis.

Design, Setting, and Participants  Randomized, double-blind controlled trial conducted in the 2 university hospitals in western Norway in 1999-2006. A total of 3096 adult participants undergoing coronary angiography (20.5% female; mean age, 61.7 years) were randomized. At baseline, 59.3% had double- or triple-vessel disease, 83.7% had stable angina pectoris, and 14.9% had acute coronary syndromes.

Interventions  Using a 2 x 2 factorial design, participants were randomly assigned to 1 of 4 groups receiving daily oral treatment with folic acid, 0.8 mg, plus vitamin B12, 0.4 mg, plus vitamin B6, 40 mg (n = 772); folic acid plus vitamin B12 (n = 772); vitamin B6 alone (n = 772); or placebo (n = 780).

Main Outcome Measures  The primary end point was a composite of all-cause death, nonfatal acute myocardial infarction, acute hospitalization for unstable angina pectoris, and nonfatal thromboembolic stroke.

Results  Mean plasma total homocysteine concentration was reduced by 30% after 1 year of treatment in the groups receiving folic acid and vitamin B12. The trial was terminated early because of concern among participants due to preliminary results from a contemporaneous Norwegian trial suggesting adverse effects from the intervention. During a median 38 months of follow-up, the primary end point was experienced by a total of 422 participants (13.7%): 219 participants (14.2%) receiving folic acid/vitamin B12 vs 203 (13.1%) not receiving such treatment (hazard ratio, 1.09; 95% confidence interval, 0.90-1.32; P = .36) and 200 participants (13.0%) receiving vitamin B6 vs 222 (14.3%) not receiving vitamin B6 (hazard ratio, 0.90; 95% confidence interval, 0.74-1.09; P = .28).

Conclusions  This trial did not find an effect of treatment with folic acid/vitamin B12 or vitamin B6 on total mortality or cardiovascular events. Our findings do not support the use of B vitamins as secondary prevention in patients with coronary artery disease.

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