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Body Weight and Mortality: New Population Based Evidences. Dongfeng Gu , MD. Fu Wai Hospital and CVD Institute Chinese Academy of Medical Sciences, Beijing, PR China, National Center of CVD, China. Background.
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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
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.
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.
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.
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.
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).
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.
BMI and CVD in the Asia-Pacific Region: 33 cohorts involving 310 000 participants Asia Pacific Cohort Studies Collaboration Int J Epidem, 2004
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
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
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
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.
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.
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.
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.
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