Longitudinal effects of body mass index on chronic diseases and functional limitations among Chinese elderly

Background. Obesity is a global epidemic. Excess body weight is widely recognized as one of the leading health threats in most countries around the world. Until recently, most populations who were obese were in the developed countries. However, in more recent decades, available data show that the most dramatic increases in obesity are in developing countries such as China. We chose Chinese elderly as our target population because China is one of the most rapidly aging and obese countries in the world, and the country's sheer size in terms of its potential economic might, populations, and the global impact of its public health. Nevertheless, literature is relatively silent on relationships between an increased body mass index (BMI) and health outcomes among Chinese elderly. Thus, this study identifies risk factors associated with an increased BMI and hypothesizes that an increased BMI will adversely affect health outcomes.

Methods. This panel data came from the China Health and Nutrition Survey (CHNS), which was designed to examine how social and economic transformation in eight provinces affects the health and nutritional status of residents. For these analyses, we used all available data from adults aged 60 years or older surveyed in 1997, 2000, 2004, and 2006 (N=3,829). Outcome variables include the BMI, the number of chronic diseases, and functional limitations, and the covariates are categorized into health-related, behavioral, demographic, and socio-economic factors. Maximum likelihood estimation will be used to estimate three separate equations to identify risk factors for an increased BMI as well as to find causality between an increased BMI and health outcomes.

Results. Around one fourth of the participants were overweight or obese. The increased odds of being overweight or obese were observed from those who consumed more calories, were female, had more income, and had health insurance. Being overweight or obese (at baseline) increased the odds of having more chronic health events but decreased that of functional limitations.

Significance of the work. This study will help us identify risk factors for obesity and evaluate the effect of an increased BMI on health outcomes among Chinese elderly. These study findings will be informative to researchers and health policymakers who are interested in China's nutritional transition among the elderly.