Ten distinct risk factors account for about 90% of global stroke risk, according to findings from the first phase of the INTERSTROKE study, a multinational, case-control study that has enrolled 6,000 patients and controls thus far.

The findings, which suggest that the stroke burden could be substantially reduced by targeted interventions to address the identified risk factors, were published online June 18 in the Lancet, and were reported simultaneously at the World Congress of Cardiology in Beijing.

Five of the risk factors that were found to be significantly associated with stroke risk accounted for about 80% of the population-attributable risk for all stroke; these were self-reported hypertension, current smoking, abdominal obesity (highest vs. lowest tertile of waist:hip ratio), diet (highest vs. lowest diet risk score), and regular physical activity. These comparisons yielded odds ratios of 2.64, 2.09, 1.65, 1.35, and 0.69, respectively.

The addition of another five significant risk factors that were identified in this study further increased the population-attributable risk for all stroke associated with these risk factors to 90%. These additional risk factors (diabetes mellitus, alcohol intake of more than 30 drinks per month or binge drinking, psychosocial stress/depression, cardiac causes, and highest vs. lowest tertile of the ratio of apolipoproteins B to A1) generally increased the odds of stroke by a smaller amount than did the other five risk factors that accounted for a greater proportion of the population-attributable risk. The comparisons generated odds ratios of 1.36, 1.51, 1.30, 1.30/1.35, 2.38, and 1.89, respectively.

All of the risk factors identified in this study were significantly associated with ischemic stroke, whereas hypertension, smoking, waist:hip ratio, diet, and alcohol intake also were significantly associated with intracerebral hemorrhagic stroke, Dr. Martin J. O’Donnell of McMaster University, Hamilton, Ontario, and his colleagues reported (Lancet 2010 June 18 [doi:10.1016/S0140-6736(10)60834-3]).

In an effort to establish the association of conventional and emerging risk factors with stroke, the INTERSTROKE investigators set out to perform a study similar to the INTERHEART study published in 2004, which identified nine modifiable risk factors that explained the majority of myocardial infarctions worldwide.

Between March 1, 2007, and April 23, 2010, the investigators studied 3,000 patients from 22 different countries, and 3,000 sex- and age-matched controls with no stroke history. Case patients (2,337 with ischemic stroke and 663 with intracerebral hemorrhagic stroke) presented with acute first stroke, and were enrolled within 5 days of symptom onset and 72 hours of hospital admission. A structured questionnaire and physical examination, including routine neuroimaging, were performed in all patients.

“Our study provides essential information on the importance of common, potentially modifiable vascular risk factors, and builds on previous epidemiological studies,” they wrote, noting that although the risk factors identified in this study are similar to those identified as being associated with myocardial infarction in the INTERHEART study, hypertension, apolipoproteins, physical activity, and alcohol intake appear to have different relative importance for stroke vs. myocardial infarction.

“These findings are important to help guide optimum selection of risk-factor targets for population-based programs to prevent all cardiovascular diseases,” the investigators concluded.

Dr. Jack V. Tu of the University of Toronto and the Institute for Clinical Evaluative Sciences, also in that city, agreed. He noted that because stroke is the second-leading cause of death globally and the cause of more than 85% of deaths in developing countries, research on risk factors for stroke around the world is imperative.

According to the INTERSTROKE investigators, hypertension is the leading risk factor for stroke not only in high-income countries, but also in developing countries. “This finding is particularly relevant because it highlights the need for health authorities in these regions to develop strategies to screen the general population for high blood pressure and, if necessary, offer affordable treatment to reduce the burden of stroke,” Dr. Tu wrote in an editorial (Lancet 2010 June 18 [doi:10.1016/S0140-6736(10)60975-0]).

He concluded that the INTERSTROKE study – although limited by its matched case-control design vs. a prospective cohort approach – nonetheless represents an efficient approach to obtaining useful information about stroke risk. The findings of this study should “help to inform stroke prevention strategies around the world and reduce the global burden of stroke.”

Phase II of the INTERSTROKE study – which is expected to include an additional 10,000 case-control pairs to more reliably characterize the importance of individual risk factors in different geographical regions, ethnic groups, and stroke subtypes – is underway and should be completed within 3 years, the investigators reported. They noted that the phase I findings confirm the feasibility of the scale of the second phase.

INTERSTROKE phase I was funded with unrestricted grants from the Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Canadian Stroke networks, Pfizer Cardiovascular Award, Merck and Co., AstraZeneca, and Boehringer Ingelheim. Multiple authors reported receiving grant/research support, honoraria, expenses, and/or fees from numerous pharmaceutical companies and other sources and/or being associated with the American Heart Association as a board member and officer.

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

国际脑卒中(INTERSTROKE)研究第一阶段研究结果发现，全球90%的卒中风险源自10种不同的危险因素，迄今，此项国际性、病例对照研究已纳入6,000例患者及对照者。

 

研究指出，对已明确的危险因素进行目标干预会极大减轻卒中负担。研究结果在线发表于6月18日的《柳叶刀》(the Lancet)上，研究者同时也在北京的世界心脏病学大会上进行了报道。

 

与卒中显著相关的5种危险因素解释了80%的所有卒中人群归因危险度。它们分别是自我报告的高血压、当前吸烟、腹部肥胖(腰臀比最高 对 最低三分位数)、节食(最高 对 最低的节食风险评分)和定期体力活动。这些比较的比值比分别为2.64、2.09、1.65、1.35和0.69。

 

如果加上此研究明确的另外5种显著危险因素，则伴有这些危险因素的所有卒中人群归因危险度进一步提高至90%。此5种危险因素(糖尿病、每月饮酒超过30杯或酗酒、社会心理压力/抑郁、心源性原因、载脂蛋白B和AⅠ比的最高 对 最低三分位数)通常较另外5种危险因素(解释了较大比例的人群归因危险度)小幅增加卒中的几率。这些比较产生的比值分别为1.36、1.51、1.30、1.30/1.35、2.38和1.89。

 

安大略省汉密尔顿麦克马斯特大学的Martin J. O’Donnell博士及其同事们报告说，此项研究所确定的所有危险因素都与缺血性卒中显著相关，而高血压、吸烟、腰臀比、节食和饮酒量也与出血性卒中显著相关(Lancet 2010 June 18[doi:10.1016/S0140-6736(10)60834-3])。

 

在试图确立常规的和新发现的危险因素与卒中之间的关系时，国际脑卒中研究者们启动了与2004年发表的国际心脏病研究相似的一项研究，后者明确了9种与全球大多数心肌梗死相关的可控危险因素。

 

2007年3月1至2010年4月23日，研究者比较了来自22个不同国家的3,000例患者以及3,000例性别及年龄相匹配的无卒中病史的对照者。患者表现为急性初发卒中(2,337例为脑缺血，663例为颅内出血)，在症状出现5天内及住院72 h内开始纳入研究。所有患者都接受了结构式问卷调查及体检，包括常规神经系统影像学检查。

 

“我们的研究立足于前期的流行病学研究之上，提供了有关常规、潜在可控的血管危险因素的重要性的基本信息”，他们写道并指出，尽管此研究确定的这些危险因素与国际心脏病研究确认的心肌梗死相关因素相似，但高血压、载脂蛋白、体力活动和饮酒量对于卒中 对 心肌梗死的相对重要性似乎有所不同。

 

研究者们总结道：“这些发现对于帮助指导基于人群的研究项目对危险因素目标进行最佳选择以预防所有心血管疾病而言非常重要。”

 

多伦多大学和位于同一城市的临床评估科学研究所的Jack V. Tu博士对此表示赞同。他指出，因为卒中是全球第二大死因，在发展中国家导致超过85%的患者死亡，所以在全球范围内对卒中危险因素进行研究势在必行。

 

据国际脑卒中研究者们报道，不管是在高收入国家还是发展中国家，高血压都是首位的卒中危险因素。Tu博士在一篇编者按中写道：“此发现尤其有意义，因为它提示了卫生当局需要在这些地区制定策略来对普通人群进行高血压筛查，并在必要时提供可支付的治疗来减轻卒中负担。”(Lancet 2010 June 18 [doi:10.1016/S0140-6736(10)60975-0])]。

 

他总结说，尽管与前瞻性队列研究相比，此项国际脑卒中研究受限于匹配的病例对照设计，但其提供了一种获得关于卒中风险实用信息的有效手段。此项研究结果将“有助于为全球卒中预防策略提供信息并降低全球卒中负担。”

 

研究者们报告说，国际脑卒中第二阶段研究已经开始并将于3年内结束，预期会纳入另外10,000对病例及对照者，旨在不同地区、民族及卒中亚型中来更可靠地描述个体危险因素的重要性。他们指出，第一阶段研究结果证实了第二阶段研究的规模可行。

 

国际脑卒中第一阶段研究资金来自加拿大卫生研究院、加拿大心脏及卒中基金会、加拿大卒中网络、辉瑞心血管奖金、默克集团、阿斯利康公司和勃林格殷格翰集团的非限制性经济补助。多位作者报告曾作为高级职员或董事会成员从众多医药公司及其他渠道[和(或)与美国心脏协会有关]接受过资金及研究支持、酬金、经费和(或)其他费用。

 

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