美国青少年膳食评分理想者不足1%

据美国心脏协会(AHA)称，如若不出台紧急、彻底的社会文化改革措施，美国年轻人的心血管健康会对其成年期乃至美国未来的公共卫生造成不良影响(Circulation 2013 April 2 [doi: 10.1161/CIRCULATIONAHA.113.001559])。

AHA继2012年对美国成人进行心血管健康分析之后开展了本研究。第一作者、奥克拉荷马大学健康科学中心的Christina M. Shay医生及其合作者对代表逾3,300万美国青少年的样本进行研究发现，膳食评分理想者不足1%。在本研究衡量的7个心血管健康要素之中，不足半数青少年具有≥5个评分理想的要素，而7个要素均达理想水平者为0人。坏消息是，美国12~19岁青少年的膳食情况堪忧，而且体力活动水平均低于维持心血管健康的最佳水平，同时还伴有胆固醇、血糖及血压水平升高的表现；而好消息是，其中大多数不良的心血管疾病危险因素都能通过改进生活方式加以调节。AHA最近发布了2020年战略影响目标，以帮助预防年轻人到成人心血管疾病的发生及维持心血管健康(Circulation 2010;121:586-613)。这2项分析提供了衡量目标进展的基线。

在本研究中，AHA以下列7个健康行为和健康因素定义心血管健康：不吸烟、体重指数、膳食摄入量、体力活动、血压、血糖及总胆固醇，并以心血管健康的复合评分定义各个类别，如0分为差，1分为中等，2分为理想。作者们对4,673名年龄介于12~19岁的受试者进行了检查，这些受试者来自2005~2010年美国国家健康与营养调查研究(NHANES)。样本的性别分布均衡，多数受试者为非西班牙裔白人(60%)，超过半数报告称家庭年收入≥45,000美元。

数据分析显示，不足半数的青少年具备≥5个AHA提出的理想心血管健康要素(男性45%，女性50%)。非西班牙裔白人男性和女性的中位心血管健康评分最高(分别为9.3和9.4分，满分为14分)，墨西哥裔男性和非西班牙裔黑人女性的评分最低(分别为8.4和8.7分)。男性，尤其是非西班牙裔白人男性，总胆固醇理想者所占比例较低，体力活动程度理想者所占比例亦较低(分别为44%和67%)。近2/3的青少年体重指数理想(男性66%，女性67%)，但非西班牙裔黑人女性和美国墨西哥裔男性中超重或肥胖的情况较多见。另外，近2/3不吸烟(男性67%，女性79%)。理想血压是最有利的心血管健康因素(男性78%，女性90%)。此外，女性中血糖理想的比例较高(89% vs. 男性74%)。大致有1/4的青少年空腹血糖属于中等水平。

Shay医生在接受采访时指出，大多数孩子出生时心血管健康状况理想，不过，不良生活方式会消耗掉这份可贵的资本。因此，在临床实践中加强青少年生活方式的改善日趋重要。这需要在父母、教育工作者、医务人员及议员的帮助下，实施重要的环境及文化改革，以推动青少年的生活方式向更健康的方向发展，从而提高美国青少年群体的心血管健康水平。

研究者坦言，本研究有多个局限性，比如尽管这些数据具有代表性，但毕竟是横向研究，不能反映个体水平的临时变化，也不足以推导出令人信服的临床疾病诊断，因此可能低估心血管健康要素的理想水平；同时，心血管健康评分并未逐一分析各个要素的影响。另外，健康因素的波动也很重要，比如总胆固醇水平在青春期会自然上升。由于NHANES是一项横向研究，因此不适宜对心血管因素做系列纵向评估，这会增加误分类的可能。

本研究获得了国家心肺血液研究所的部分资助。除Stephen R. Daniels外，其他作者均无任何披露内容，Stephen R. Daniels是默克制药公司数据安全性监测委员会的主席。

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By: NASEEM S. MILLER, Cardiology News Digital Network

A snapshot of cardiovascular health in today’s youth bears no good news for their adult years or the future of the country’s public health, unless there are immediate and sweeping social and cultural changes, according to the American Heart Association.

The AHA’s examination of a sample representing more than 33 million U.S. adolescents showed that less than 1% had an ideal diet score. Less than half of adolescents achieved an ideal score in five or more of the seven cardiovascular health components measured in the study. None had ideal levels in all seven categories.
 
“The bad news is that an alarming proportion of US children between 12-19 years currently have poor levels of dietary intake and less than optimal levels of physical activity to maintain cardiovascular health,” said study’s lead author Christina M. Shay, Ph.D., University of Oklahoma Health Sciences Center, Oklahoma City. “These unfavorable lifestyle habits have likely already led to the high proportion of children in this study to also exhibit elevated levels of cholesterol, blood glucose, and blood pressure.” (Circulation 2013 April 2 [doi: 10.1161/CIRCULATIONAHA.113.001559]).

The good news, she said, “is that most of these unfavorable cardiovascular disease risk factors are modifiable through implementation of lifestyle change.”

The study follows a 2012 analysis of cardiovascular health in U.S. adults (Circulation 2012;125:45-56).

The AHA recently released the 2020 Strategic Impact Goals to help prevent cardiovascular disease and maintain cardiovascular health from youth throughout adulthood (Circulation 2010;121:586-613). The two analyses provide a baseline to measure progress toward that goal.

AHA defines cardiovascular health by seven health behaviors and factors: no smoking, body mass index, dietary intake, physical activity, blood pressure, blood glucose, and total cholesterol. It quantifies each category with a composite score for CV health with 0 for poor, 1 for intermediate, and 2 for ideal.

The authors examined components of cardiovascular health in 4,673 participants between ages 12 and 19 years from the 2005 to 2010 National Health and Nutrition Examination Surveys (NHANES). The sample group provides an estimated representation of 33.2 million U.S. adolescents.

The sample was well-balanced by sex. The majority of participants were non-Hispanic white (60%), and more than half reported an annual household income of $45,000 or more.

The examination of the data showed that fewer than half of adolescents exhibited five or more of AHA’s ideal cardiovascular health components (45% males and 50% females). Of the maximum score of 14, non-Hispanic white males and females had the highest median Cardiovascular Health Score (9.3 and 9.4 respectively). Mexican American meals and non-Hispanic black females had the lowest score (8.4 and 8.7 respectively).

Females, especially non-Hispanic whites, had a lower prevalence of ideal total cholesterol (65% females v. 72% males), and ideal physical activity (44% v. 67%).

Nearly two-third of the adolescents had an ideal body mass index (66% males and 67% females), but non-Hispanic black females and Mexican American males were more overweight or obese compared with non-Hispanic whites.

Also, nearly two-thirds had ideal smoking status (67% males and 70% females). Ideal smoking status was the most prevalent CV health behavior in all sex and race/ethnicity groups, especially among non-Hispanic blacks.

Ideal blood pressure was the most favorable cardiovascular health factor (78% males and 90% females.)

Meanwhile, females had a higher prevalence of ideal blood glucose (89% v. 74% males). Non-Hispanic blacks had the highest prevalence of ideal fasting blood glucose compared with non-Hispanic whites and Mexican Americans. Roughly a quarter of all adolescents had intermediate fasting blood glucose levels.

“Most children are born in a state of ideal cardiovascular health,” Dr. Shay said in an interview. “However, the poor lifestyles many U.S. children exhibit are leading to a loss of this important asset earlier and earlier in life. A stronger focus on emphasizing improvements in adolescent lifestyles needs to be implemented in the clinical setting.”

She added that “significant environmental and cultural changes need to be implemented with the assistance of parents, educators, health professionals, and legislators to promote healthier lifestyles of adolescents (and people of all ages) in order to improve the cardiovascular health of the US adolescent population.”Dr. Shay said her research team is currently comparing the cardiovascular health of the study’s population from 10 years ago to what it is today. “Considering the direction things have been going from then to now, we are estimating what things are going to look like in the year 2020.”

Her team is also working on estimating costs.

The study has several limitations, according to the authors. Although the data are nationally representative, they are cross-sectional and don’t represent temporal changes at an individual level. The data are also insufficient to obtain a confident diagnosis of clinical disease and as a result may underestimate ideal levels of CV health components. Also, the Cardiovascular Health Score does not weight the influence of each individual component, "and should be interpreted in light of this limitation," the authors noted.

They also noted that it is important to consider the fluctuations in health factors – such as increases in total cholesterol levels – that occur naturally during puberty and adolescence. Since NHANES is a cross-section, it does not allow for serial evaluation of CV factors, which could as a result increase the likelihood of misclassification.

The study was supported in part by a grant from the National Heart, Lung, and Blood Institute. None of the authors reported any disclosures except for Dr. Stephen R. Daniels who was the chair of the Data Safety and Monitoring Board for Merck Pharmaceuticals.