1. Department of Epidemiology &Biostatistics School of Public Health, Xinjiang Medical University

2. Ethnic difference in blood pressure in Xinjiang Han, Uygur and Kazak children and adolescents Yan WL, Ma Jinfeng, Wang Qian, Dai JH, Yao H, Yang XY, Zheng YJ Corresponding: Weili Yan 严卫丽 01.weili@gmail.com Tel&Fax: 0991-4366351 Department of Epidemiology &Biostatistics School of Public Health, XJMU

3. Ethnicities in Xinjiang Uygur Kazak 38% 46% 3% 13%

4. Background 1. The risk of common complex diseases, essential hypertension, type 2 diabetes and obesity differs among Uygur and Kazak adult populations. (1) 2. Ethnic difference in fat distribution was observed between Uygur and Kazak adult populations. (1) 3. Ethnic difference in BMI levels and prevalence of overweight and obesity in pediatric populations (2)

5. Fig1. Prevalence of EH among Ethnic Adults The Chinese Task Force of National Survey of Hypertension. Chin J Hypertens 1995;3 (suppl): 14-18 kazak Uygur Han Ethnic groups

6. Table 1. Prevalence studies on metabolic diseases in adult populations (2005 ） DiseasePrevalence,% UygurKazakChina* Hypertension 1 9.150.018.6 Diabetes 2 4.00.12.6 Obesity 3 8.135.45.6 * The 4th national survey of nutrition and health, 2002 1.Hypertension: SBP ≥ 140 and/or DBP ≥ 90 or under medication 2.Diabetes: FBS ≥ 7.0 mmol/L 3.Obesity: BMI ≥ 28 kg/m 2

7. Fig 2 ． Age-adjusted prevalence of overweight&obesity in Han, Uygur, Kazak and Hui ethnic children and adolescents aged 7-18 (2004) The prevalence of obesity are 4.3% ， 3.8% ， 2.1% ， and 0.2% for boys; as well as 1.4% ， 0.8% ， 0.5% ， and 0.15% for girls, defined by IOTF cutoffs.

8. Source of data 1. The routine data (2003) of school-aged children aged 7-18 from New District of Urumqi City organized by the National Educational Ministry Physical Examination Center 2. The cross-sectional study based on a school- based random sample ( recruited stratified by age and gender children aged from 7 to 18 years in Urumqi city in 2005)

9. Study population of the cross sectional study 1. A representative sample of school children aged form 7 to 18 years were recruited by randomly systematic and clustering sampling by age and gender in Urumqi city and Altai city in 2005. 2. Eleven schools, 115 classes, over 6600 students involved. 3. Including Uygur, Han and Kazak ethnicities.

10. Data collection 1. A set of questionnaire including demographic data of students and their parents, known risk factors of obesity, such as diet, life style and physical activity etc. 2. Anthropometric measurements Including weight, height, waist and hip circumference, were recorded with the standard protocol and instruments by professional investigators. Weight was measured with minimal clothing, and standing height was measured without shoes, with a precision of 0.5 kg and 0.5 cm, respectively, following the national protocol.

11. Blood pressure measurement Measured in afternoon time; At least 5 minutes rest before measurement; Manual standard mercury manometers were used and had been calibrated by the same laboratory before investigation and appropriate size of cuff were used; Sit position, right arm Measured twice with at least 30 seconds interval; Korotkoff phase I and V sounds were checked as SBP and DBP respectively; Deflated by around 2 mm Hg each second; All readings were taken to the nearest 2 mm Hg.

12. Is double measurement of blood pressure safe?-1 A pilot study included 401 volunteers aged from 5-69 years Age groupn 5-10115 11-17190 18-69100

13. Blood pressure were measured strictly by the standard protocol recommended by AHA. We compared the average SBP and DBP from the first 2 measurements and the whole 3 measurements. Is double measurement of blood pressure safe?-2

14. Table 2. Average blood pressure by first 2 and all 3 measurements Blood pressure Average of first 2 Average of 3Sig. All subjectsSBP, mm Hg108.0±11.2107.9±10.90.9977 DBP, mm Hg67.89±19.667.5±14.60.8740 Subjects aged 5-18 SBP, mm Hg107.7±10.9107.5±10.70.9890 DBP, mm Hg66.5±9.266.4±9.00.828 Well trained investigator make it possible to measure blood pressure twice in field work.

15. Fig3. The prevalence of hypertension in Han and Uygur school-aged populations (2005 data) The Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents

16. Fig4-a. Height centile curve for American ( 2000 CDC data) and Chinese (2005 cross-sectional data) school-aged boys (LMS smoothed)

17. Fig4-b.. Height centile curve for American ( 2000 CDC data) and Chinese (2005 cross-sectional data) school-aged girls (LMS smoothed)

18. Fig 5-a. The mean height of Uygur, Han and Kazak children and adolescents aged 7-18yrs ( Boys)

19. Fig5-b. The mean height of Uygur, Han and Kazak children and adolescents aged 7-18yrs ( Girls)

20. Fig 6. The mean SBP of Han, Uygur and Kazak children and adolescents adjusted by age and height, mm Hg P<0.001 Male Female

21. Fig 7. The mean DBP of Han, Uygur and Kazak children and adolescents adjusted by age and height, mm Hg P<0.001 Male Female

22. Fig 8. The age adjusted mean HEIGHT of Han, Uygur and Kazak children and adolescents by age. (cm)

23. Fig 9. The age adjusted mean BMI of Han, Uygur and Kazak children and adolescents by age. (cm)

24. Does the difference in height and BMI among ethnicities make the ethnic difference in blood pressure ?

25. Table 3. The explained variation (EV) of SBP by height in Han, Uygur and Kazak pediatric populations EV,%UygurHanKazak Full model 9.819.66.5 BMI_pct 5.87.33.3 Height, cm 1.72.91.3 Age, years 0.10.20.1 Full model includes BMI, height and age as independent variables. EV % were analyzed by adjusted R 2 of full model minus that from the reduced model by removing height, BMI or age respectively BMI_pct, age-specific percentile

26. Table 4. The explained variation (EV) of DBP by height in Han, Uygur and Kazak pediatric populations EV,%UygurHanKazak Full model 2.03.15.8 BMI_pct 0.050.022.5 Height, cm 1.72.21.3 Age, years 0.070.02.4 Full model includes BMI, height and age as independent variables. EV % were analyzed by adjusted R 2 of full model minus that from the reduced model by removing height, BMI or age respectively BMI_pct, age-specific percentile

27. Conclusions-1 1. There is ethnic differences in SBP, DBP, height and BMI among Uygur, Han and Kazak school-aged children and adolescents. 2. Height, BMI and age explain greater variation of SBP in Han but DBP in Kazak population than that in the other two ethnic pediatric populations.

28. 3. The rest risk factors out of height, BMI and age, e.g., genetic factors, may contribute more to DBP levels but less to SBP in Kazak children than that in Uygur and Han counterparts. Conclusions-2

29. References 1. Yan W, Yang X, Chen S et al. Ethnic Differences in Body Mass Index and Prevalence of Obesity in School Children of Urumqi City, Xinjiang, China. Biomed Environ Sci. 2006 Dec;19(6):469-73. 2. Yan W, Yang X, Zheng Y, Ge D, Zhang Y, Shan Z, Simu H, Sukerobai M, Wang R. The metabolic syndrome in Uygur and Kazak population. Diabetes Care. 2005 ， 28 （ 10 ）： 2554-5.

30. Other published papers based on the same study sample 3.Yan W, Yao H, Dai J, Chen Y, Cui J, Wang X. Waist circumference cutoff points for Chinese children and adolescents. Obesity. 2008;16(5):1687-1692 4.Yan W, He B, Wang X, et al. Waist-to-Height Ratio Is an Accurate and Easier Index for Evaluating Obesity in Children and Adolescents. Obesity (Silver Spring). 2007 Mar;15(3):748-52. 5.Yan W, Wang X, Yao H et al. Waist-to-height Ratio and BMI Predict Different Cardiovascular Risk Factors in Chinese Children. Diabetes Care. 2006; 29(12):2760-1. 6.Yan W, Gu D, Yang X, Wu J, Kang L, Zhang L. High-density lipoprotein cholesterol levels increase with age, body mass index, blood pressure and fasting blood glucose in a rural Uygur population in China. J Hypertens. 2005;23 (11):1985-1989.

31. Thank you !