Body Weight and Mortality: New Population Based Evidences

1. Body Weight and Mortality: New Population Based Evidences DongfengGu, MD Fu Wai Hospital and CVD Institute Chinese Academy of Medical Sciences, Beijing, PR China, National Center of CVD, China

2. Background • Prevalence of overweight and obesity has increased in China and in other economically developing countries. • The prevalence of overweight and obesity is essential for strategies of effective prevention and control for obesity, diabetes, hypertension and CVD. • The effect of underweight and obesity on mortality has not been well characterized in Asian populations.

3. Background • Obesity is a strong risk factor for diabetes, coronary heat disease, stroke, and some types of cancer. However, the association between body weight and all-cause mortality is more controversial: a direct association or a J-shaped or U-shaped relationship have been reported in recent studies . • Most of these studies have been conducted in Western populations with only a small proportion of the study participants have had a low body-mass index.

4. Background • Several epidemiological studies have suggested that Asian populations have higher amounts of body fat and prevalence of cardiovascular disease risk factors at lower levels of body-mass index compared to their counterparts in Western populations. • WHO, IASO, and IOTF have suggested lower BMI cutoffs for overweight (23.0-24.9 kg/m2) and for obesity (≥25.0 kg/m2) in Asian populations, labeling these recommendations as provisional and calling for their validation in clinical and epidemiologic studies.

5. CHEFS - Objectives • The Chinese National Hypertension Survey Epidemiologic Follow-up Study (CHEFS). • Prospective cohort study in a nationally representative sample of 169,871 Chinese men and women aged 40 years and older. • To examine the relation between body weightand risk of CVD, cancer or other causes of death in the Chinese Adult population.

6. Methods – Definitions • Multivariate-adjusted relative risk was calculated using study participants with a body-mass index of 24.0-24.9 kg/m2 as the reference because this group had the lowest mortality. • Cox proportional hazards models were used to adjust for baseline age, gender, cigarette smoking, alcohol consumption, physical activity, education, geographic region (north vs. south) and urbanization (urban vs. rural).

7. Results • During an average follow-up of 8.3 years (1,113,162 person-years), 17,687 deaths were documented. There was a statistically significant U-shaped association between body-mass and age-standardized mortality from all-causes (p<0.0001) with the lowest mortality among study participants with a body-mass index (kg/m2) of 24.0-24.9 in men and 25.0-26.9 in women.

10. Age <65 Years (7621 deaths)

11. Age ≥65 Years (10066 deaths)

12. Never-Smokers (9894 deaths)

13. Current or Former Smokers (7775 deaths)

14. No History of Disease at Baseline (15925 deaths)

15. Not Died in First 3-Years of Follow-up (12473 deaths)

16. No Heavy Alcohol Drinkers (16370 deaths)

17. Cardiovascular Mortality (8079 deaths)

18. Cancer Mortality (3929 deaths)

19. Other Cause Mortality (5679 deaths)

21. Prospective Studies Collaboration in China

24. BMI and CVD in the Asia-Pacific Region: 33 cohorts involving 310 000 participants Asia Pacific Cohort Studies Collaboration Int J Epidem, 2004

25. Other Cause Mortality (5679 deaths)

26. Age-Standardized Prevalence of Overweight and Obesity in the Adult Population Aged 35-74 Years by Geographic Region and Urbanization in China, 2000-2001 ≥ 25.0 ≥30.0 BMI, kg/m2

27. Age-Standardized Prevalence of BMI Cut-points Among Men and Women Aged 35-74 Years in China, 2000-2001  23.0  24.0  25.0  28.0  30.0 BMI, kg/m2

28. Estimated Number of Overweight and Obese Adults Aged 35-74 Years in China, 2000-2001 ≥ 23 kg/m2 ≥ 24 kg/m2 ≥ 25 kg/m2 ≥ 28 kg/m2 ≥ 30 kg/m2

29. Results • During an average follow-up of 8.3 years (1,113,162 person-years), 17,687 deaths were documented. There was a statistically significant U-shaped association between body-mass and age-standardized mortality from all-causes (p<0.0001) with the lowest mortality among study participants with a body-mass index (kg/m2) of 24.0-24.9 in men and 25.0-26.9 in women.

30. Conclusion • The lowest rates of death from all-causes were at a body-mass index between 24.0-24.9 kg/m2 in Chinese men and 25.0-26.9 kg/m2 in Chinese women. • BMI <18.5 or 18.5-22.9 kg/m2) had a significantly increased all-cause mortality. • BMI > 27.0 in men and >30.0 in women was associated with an increased all-cause mortality.

31. Conclusion • It certainly indicate that BMI <18 at the highest risk of any kind of death. The risk of cancer, CVD and other causes of death decreased with BMI from 18-27.9. The risk only increased after BMI>=28, but is still lower than BMI at 18-22, for CVD, cancer and other causes of death. • Western populations have identified the lowest all-cause mortality among persons with a body-mass index between 23 and 27.

32. Conclusion • The U-shaped association was observed between body weight and mortality from cardiovascular disease, cancer, and other causes. • The current studies indicates that both underweight and obesity were associated with increased mortality in the Chinese adult population. Furthermore, our findings support the use of a single common recommendation for defining overweight and obesity among all race and ethnicity groups.

33. Acknowledgement • Participating Institutes • Cardiovascular Institute of Chinese Academy of Medical Sciences, Beijing, China • 10 Provinces including • Fujian, Guangxi, Jiangsu, Hubei, Sichuan, • Shandong, Beijing, Jilin, Shanxi, Qinghai • Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA • Institute for International Health, University of Sydney, Sydney, Australia • National Health Foundation, Mahidol University, Bangkok, Thailand