Changes in body mass index before and during economic development and subsequent risk of mortality: a 35-year follow-up study in China

He, Yao

Changes in body mass index before and during economic development and subsequent risk of mortality: a 35-year follow-up study in China

Monday, 18 August 2014

Exhibit hall (Dena'ina Center)

Yao He, PhD , Chinese People's Liberation Army General Hospital, Beijing, China

Tai Hing Lam, MD , The University of Hong Kong, Hong Kong, Hong Kong

Bin Jiang , Chinese People's Liberation Army General Hospital, Beijing, China

Lan Sun Li , 4th Military Medical University, Xi'an, China, Xi'an, China

Dong Ling Sun , Chinese People's Liberation Army General Hospital, Beijing, China, Beijing, China

Lei Wu , Chinese People's Liberation Army General Hospital, Beijing, China

Miao Liu , Chinese People's Liberation Army General Hospital, Beijing, China

Shan Shan Yang, MD , Chinese People's Liberation Army General Hospital, Beijing, China

Yi Yan Wang , Chinese People's Liberation Army General Hospital, Beijing, China

Deirdre K. Tobias , Harvard School of Public Health, Boston Massachusetts, Boston, MA

Qi Sun , Harvard School of Public Health, Boston Massachusetts, Boston, MA

Frank B. Hu , Harvard School of Public Health, Boston Massachusetts, Boston, MA

INTRODUCTION:

It is unclear whether changes in body mass index (BMI) during rapid economic development influence subsequent mortality.

METHODS:

We analyze whether BMI in 1976 and 1994, and changes in BMI during 1976-1994 predict cardiovascular disease (CVD) and all-cause mortality in a 35-year follow-up cohort of 1,696 Chinese (1,124 men and 572 women, aged 35-65 years) in Xi'an, China. Participants were categorized as underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), and overweight (≥25.0 kg/m²).

RESULTS:

During 51,611 person years of follow-up, we identified 655 deaths from all-causes and 234 from CVD. From 1976-1994, the prevalence of overweight rose from 9.2% to 27.8%. With each 1 unit increment in 1976 BMI, multivariate hazard ratios (HRs) (95%CI) were 0.78 (0.72-0.84) for CVD and 0.91(0.87-0.95) for all-cause mortality. In contrast, corresponding HRs were 1.14 (1.08-1.19) and 1.05 (1.01-1.08) in 1994 BMI. The HRs for each unit increment in BMI change from 1976-1994 were 1.35 (1.25-1.41) for CVD and 1.09 (1.05-1.13) for all-cause mortality. Compared to participants with stable normal weight in 1976 and 1994, HRs of all-cause mortality for those who had normal weight in 1976 but became overweight in 1994 and for those who were persistently overweight during 1976-1994 were 1.42 (1.12-1.80) and 1.80 (1.04-3.14), respectively.

CONCLUSIONS:

Gaining weight with increased BMI at middle or older age in Chinese during economic development was associated with elevated risks of all-cause and CVD mortality. Higher BMI measured before development was associated with lower mortality risk, whereas BMI measured afterwards was associated with increased mortality. Our findings suggest that if the relationships are causal, about half of those who were overweight during the entire follow-up would be killed prematurely by their persistent overweight and one-third of the people who became overweight during 18 years of rapid economic development in China would be killed by diseases associated with weight gain.