我國南北血壓差異及其膳食因素的作用——營養(yǎng)與血壓的國際

1、我國南北血壓差異及其膳食因素的作用——營養(yǎng)與血壓的國際合作研究(INTERMAP Study),中國醫(yī)學科學院心血管病研究所 阜外心血管病醫(yī)院趙連成 周北凡 武陽豐,INTERnational collaborative study on MAcronutrients and Blood pressure(Financially supported by NHLBI),INTERMAP 研究簡介,INTERMAP 研究背景

2、,一般人群中，人群血壓水平從中年開始明顯增加；而在一些特殊人群中，人群血壓水平沒有隨年齡增加或增加不明顯；移民流行病學研究提示，人群血壓水平以及血壓隨年齡增加的現象與生活方式有關；已有的研究提示生活方式如膳食因素(BMI、鈉、鉀、飲酒等）因素與血壓有關；缺乏高質量的、大規(guī)模、不同人群背景的研究；,INTERMAP 主要研究目的,探討多種膳食營養(yǎng)因素與血壓的關系。,INTERMAP研究特點,橫斷面研究；4個國家，17個研究人群；

3、中年人群，40－59歲，共4680人；高質量的研究方法，包括統(tǒng)一、高質量的膳食調查方法；具有可比性的食物成分表評估營養(yǎng)素的攝入量。,INTERMAP Field Centers: China營養(yǎng)與血壓關系的國際合作研究,,.,.,.,BeijingShanxiGuangxi,,,,,INTERMAP Field Centers: Japan,,Sapporo,.,,.,.,.,,,Toyama,,,Aito Town,,

4、,,Wakayama,,,,INTERMAP Centers: United Kingdom,,.,.,.,BelfastBirminghamLondon (Coordinating Center),,,,Minneapolis Chicago,INTERMAP Field Centers: United States,,Pittsburgh,Baltimore,Jackson,Houston,Corpus Chr

5、isti,Honolulu,,.,.,,.,,.,,.,,.,.,.,,,,Background,Blood pressure (BP) and prevalence of high BP are greater for northern than for southern Chinese.Although a few studies suggest that heavier body mass and higher salt int

6、ake in the north are related to these BP differences, these unfavorable characteristics only partially explained the north-south BP differences.,Purpose,To evaluate multiple dietary factors in determining North-South BP

7、 differences in China.,Study Population,There are three Chinese rural samples, two from the North (Pinggu Conuty, Beijing, and Yu County, Shanxi ) and one from the South (Wuming County, Guangxi);Population-based sample;

8、260 persons (1 per family) was randomly selected from each target population, stratified by gender 10-year age group.,Measurements,Field work was conducted in 1997-1998.Each participant attended the local center on fou

9、r occasions – two pairs of consecutive days about 3-6 weeks apart.Blood pressure was measured twice at each visit with a random zero sphygmomanometer.Height and weight without shoes or heavy clothes were measured at th

10、e first and third visits.,Dietary Measurements,Dietary data were collected at each of the four visits by standardized 24-hour dietary recalls.Nutrients were calculated with use of an extensive database, derived from the

11、 Chinese national food table and enhanced by the Nutrition Coordinating Center (NCC), University of Minnesota. Two timed 24-hour urine specimens were collected. Urine aliquots were stored frozen at -20oC and then air-

12、freighted frozen to the Central Laboratory where urinary Na, K, and other indices were measured.,Quality Control,INTERMAP protocol, Manuals of Operation;China addendum to the Nutrition Manual (including Chinese Coding M

13、anual); All stuff trained and certificated;Central training and certification for all dietary interviewers;‘Dry run’;Standard food models, calibrated utensils, scales, pictures,etc.;,Quality Control-- continued,Colle

14、cted information from cooks;Monitoring of interviewers during field work;Tape recording of all interviews, review of randomly selected tape and timely feedback to the interviewers;Dietary data coded on survey day; Da

15、ily local recording of 10% of recalls by Site Nutritionist and feedback;Recording of 10% of randomly selected recalls by Country Nutritionist and feedback to local centers timely.,Statistical Methods,Measurements for ea

16、ch individual were averaged across visits. Two northern samples (Beijing and Shanxi) were combined as a “North” sample set (Since BP levels as well as most dietary and non-dietary variables were similar for them), and

17、Guangxi sample was designated the “South” sample.Multiple linear regression models were used to examine relations of dietary factors to North-South differences in SBP/DBP.,Average SBP by Sample (Men and Women Combined,

18、 N=839),Compared to the South (Guangxi), all P-values<0.001),,Compared to the South (Guangxi), all P-values<0.001),Average DBP by Sample (Men and Women Combined, N=839),Mean or Prevalence of Selected Variables by

19、Sample (Men and Women Combined, N=839),* P<0.001 for North vs South (t test or ?2 test),Mean Nutrient Intake by Sample,* P<0.001 for North vs South (t test or ?2 test),Mean Nutrient Intake by Sample -- continued,

20、* P<0.001 for North vs South (t test or ?2 test),Relations of Variables Considered Singly to North-South SBP/DBP Differences,* Coefficient for difference in BP (mm Hg ) between North and South.? Percent reduction in

21、site-BP coefficient compared to Model 1.,,* Coefficient for difference in BP (mm Hg between North and South.? Percent reduction in site-BP coefficient compared to Model 1.,Relations of Variables Considered Singly to Nor

22、th-South SBP/DBP Differences -- continued,,,* Coefficient for SBP difference (mm Hg) between the North and the South. ? Percent reduction in site (North-South)-SBP coefficient compared to Model 1 (without BMI).? Perc

23、ent reduction in site (North-South)-SBP coefficient compared to Model 2 (without BMI). § P- value>0.05,Relations of Combinations of Dietary Variables to North-South SBP Differences,,,* Coefficient for DBP diffe

24、rence (mm Hg) between the North and the South. ? Percent reduction in site (North-South)-DBP coefficient compared to Model 1 (without BMI).? Percent reduction in site (North-South)-DBP coefficient compared to Model 2

25、 (without BMI). § P- value>0.05,Relations of Combinations of Dietary Variables to North-South DBP Differences,Summary,Northern Chinese had significantly higher SBP/DBP (7.4/6.9 mm Hg higher) than Southerners.

26、In general, Southerners had putatively healthier lifestyles than Northerners, e.g., lower BMI and sodium intake, and higher physical activity and micronutrient intake (vitamin A, vitamin C, calcium, magnesium, phosphoru

27、s). Combinations of several dietary variables – especially Na, K, phosphorus or magnesium, and BMI – reduced North-South BP differences to non-significant levels.,Conclusion,Multiple dietary factors account importantly

28、for North-South BP differences in China.In addition to the known importance of maintaining an optimal body weight and lower salt intake, higher intake of certain micronutrients may be valuable measures to improve popula