The diminishing socioeconomic disparity in obesity in a Chinese population with rapid economic development: analysis of serial cross-sectional health survey data 2002-2010.

BACKGROUND: Social changes and economic development are associated with obesity epidemic. This study is to investigate the trends of socio-economic disparity in obesity from 2002 to 2010 in a Chinese population experiencing the world's fastest economic development.

METHODS: Four standardized surveys were conducted in a population of 85 million residents in Guangdong, China between 2002 and 2010. Multistage random cluster sampling was used to recruit representative samples. Information on socio-economic status (SES), proxied by education, occupation and residential area, was collected by face-to-face interviews. The weight, height and waist circumference of the participants were also measured.

RESULTS: Women with low education had an increased BMI of 0.85 kg/m(2), while women with high education had a decreased BMI of 0.16 kg/m(2) (p = 0.032 for interaction test). Similar trends were observed by using occupation and residential area as the SES indicators. Analysis in men yielded similar patterns. Waist circumference increased from 73.7 to 78.4 cm, and the increasing trends of statistical significance (p < 0.01) were observed in both genders and across all SES levels, with the magnitudes of increase in low SES levels being more pronounced. The impact of gradient in food attainment and occupational physical activity across the SES levels may wear off with further economic development, while factors such as health awareness, diet pattern and leisure activity may become increasingly important in driving the disparity.

CONCLUSION: The impact of gradient in food attainment and occupational physical activity across the SES levels may wear off with further economic development, while factors such as health awareness, diet pattern and leisure activity may become increasingly important in driving the disparity. Our findings suggest that health education should focus on the disadvantaged populations on health awareness for adopting healthier diet pattern and increasing physical activity.