Trends in overweight by socio-economic status in Vietnam: 1992 to 2002

Objective: To explore socio-economic factors associated with rising rates of overweight among Vietnamese adults. Design: The study was based on three national surveys of socio-economic factors and health conducted over a 10-year period. The studies were: the Vietnamese Living Standard Survey 1992-1993 (11982 participants); the Vietnamese Living Standard Survey 1997-1998 (15 975 participants); and the Vietnamese National Health Survey 2001-2002 (94656 participants). Subjects: Male and female adults > 18 years old were stratified by gender, age group, area of residence, occupation, education and relative food expenditures. Overweight was defined using body mass index (BMI) >= 25 kg m(-2). Results: Overweight rates in Vietnam more than doubled between 1992 and 2002 (from 2.0 to 5.7%). Significant increases were observed for men and women, in urban and rural areas, and for all age groups. In univariate analyses, both age and higher socio-economic status were associated with higher rates of overweight. Using the most recent survey, urban populations were more likely to be overweight than rural ones (odds ratio (OR) = 1.79), white-collar workers were more likely to be overweight than manual labourers (OR = 1.95) and persons in the top level of food expenditures were more likely to be overweight than persons in the bottom level (OR = 4.96) after adjustment for other factors. Education was inversely associated with overweight after adjusting for covariates. Conclusion: Economic growth and improved standard of living are associated with higher rates of overweight in nations in early stages of economic development. In Vietnam, higher rates of overweight were observed among the higher income and occupation groups.