An Increasing Socioeconomic Gap in Childhood Overweight and Obesity in China

摘要

We used a new conceptual framework that integrates tenets from health economics, social epidemiology, and health behavior to analyze the impact of socioeconomic forces on the temporal changes in the socioeconomic status (SES) gap in childhood overweight and obesity in China. In data from the China Health and Nutrition Survey for 1991 to 2006, we found increased prevalence of childhood overweight and obesity across all SES groups, but a greater increase among higher-SES children, especially after 1997, when income inequality dramatically increased. Our findings suggest that for China, the increasing SES gap in purchasing power for obesogenic goods, associated with rising income inequality, played a prominent role in the country’s increasing SES gap in childhood obesity and overweight. It is well documented that family socioeconomic status (SES) is associated with childhood overweight and obesity 1–3 ; however, the pathways linking SES with overweight and obesity may be strongly conditioned by a country’s stage of economic development. For example, an inverse relationship between SES and obesity is typically observed among children in developed countries, 2,4 whereas in many developing countries, overweight and obesity are more common among socioeconomic elites. 1,5,6 Several questions are unanswered: What contextual factors connect the stage of economic development with the sign and strength of the association between SES and childhood overweight and obesity? What is the relative importance of these factors? What happens when these contextual factors exert contradictory effects on risk for childhood obesity and overweight? The dramatic social and economic changes in China that took place after 1997 provided a unique opportunity to explore these questions. Until now, the only study of the change in the SES–overweight and obesity association among Chinese children focused on the annual change in overweight prevalence by income. 7 This study found that overweight prevalence increased fastest among high-income children between 1991 and 2004. To date, however, no study has thoroughly explored the contextual factors contributing to the changing relationship between SES and overweight and obesity in children and adolescents, in China or in any other developing country. The direction of causality between SES and obesity for children is relatively easy to discern, because their SES is predetermined by that of their parents; hence, their obesity status is unlikely to affect their childhood SES. 1 We developed a conceptual framework to address specific contextual factors that could shape the SES–childhood overweight and obesity relationship. We test several major tenets of this framework in data collected from 1991 to 2006 by the China Health and Nutrition Survey (CHNS). 8.