Longitudinal sedentary behavior changes in adolescents in Ho Chi Minh City.

BACKGROUND: Sedentary behavior is associated with increased risk of chronic disease and sedentary behavior is increasing among adolescents. Data on changes in sedentary behavior in developing countries are limited. PURPOSE: To describe 5-year longitudinal changes in nonschool sedentary hours among urban adolescents in Ho Chi Minh City, and to identify correlates with this change. METHODS: This is a 5-year longitudinal cohort with systematic random sampling of 759 students from 18 junior high schools. All measures were taken annually between 2004 and 2009. Sedentary behavior was assessed by self-report and accelerometry. Generalized linear latent and mixed models were used to analyze the data in 2011. RESULTS: Between 2004 and 2009, self-reported time spent in nonschool sedentary behavior increased from 498 to 603 minutes/day. In the 5th survey year, boys and girls (aged 16 years) were, respectively, 3.6 times (95% CI=2.3, 6.0) and 3.1 times (95% CI= 1.8, 5.0) more likely to spend ≥2 hours/day on screen time compared with baseline (aged 12 years). Accelerometer data adjusted for wearing time revealed that boys and girls aged 16 years had, respectively, 78 minutes/day (95% CI=48, 104) and 69 minutes/day (95% CI=34, 95) more nonschool sedentary time than those at the first accelerometer assessment (at age 13 years). Girls in the highest socioeconomic quartile spent an additional 90 minutes/day in sedentary behavior compared with girls in the lowest quartile (95% CI=52, 128). CONCLUSIONS: Nonschool sedentary behavior increased among Vietnamese adolescents with age. The largest increase was in recreational screen time (28%), which would be the most obvious target for preventive health strategies.

Factors associated with physical inactivity in adolescents in Ho Chi Minh City, Vietnam.

PURPOSES: To identify factors associated with physical inactivity among adolescents in Ho Chi Minh City (HCMC). METHODS: A cross-sectional survey was conducted in 2004 among 2684 junior high school students using multistage cluster sampling. Time spent for physical and sedentary activities was collected with a validated questionnaire. Anthropometry, parental/family characteristics, neighborhood, and school environments were also measured. Level of activity was classified as physically active or inactive using standard criteria. Potential risk factors for physical inactivity were identified with hierarchical multivariate logistic regression, stratified by gender. RESULTS: Physical inactivity was positively associated with child's overweight status (odds ratio [OR] = 2.5, 95% confidence interval [CI] = 1.9, 3.2), passive transportation (OR = 4.2, 95% CI = 3.3-5.2), not having recess exercises (OR = 1.3, 95% CI = 1.1-5.6), availability of a nearby game shop (OR = 1.8, 95% CI = 1.5-2.2), more time spent playing video games, watching television, and studying after class (OR = 2.3, 95% CI = 1.7-3.1; OR = 1.5, 95% CI = 1.2-1.9; and OR = 1.8, 95% CI = 1.3-2.4, respectively). The following factors decreased the odds of inactivity: schools having one to two sport meetings per year (OR = 0.7, 95% CI = 0.5-1.0), availability of a play yard (OR = 0.7, 95% CI = 0.6-0.9), older age group (OR = 0.2, 95% CI = 0.1-0.2), and male gender (OR = 0.6, 95% CI = 0.5-0.7). In boys, transportation, school sport meeting, availability of game shop near by, family's economic status, parental body mass index status, and time spent watching television were strongly associated with physical inactivity. In girls, time spent for study after class was one of the most important factors related to students' physical inactivity. CONCLUSIONS: Physical activity among adolescents in HCMC is related to household, school, and community factors. These factors and gender differences should be taken into account when promoting physical activity in adolescents.

Overweight and obesity are rapidly emerging among adolescents in Ho Chi Minh City, Vietnam, 2002-2004.

OBJECTIVE: To assess changes in the prevalence of overweight and obesity among adolescents in urban districts of Ho Chi Minh City between 2002 and 2004. METHODS: Two surveys were conducted among high school students (11-16 years) in 2002 (n = 1003 students) and 2004 (n = 2684). International Obesity Taskforce (IOTF) sex and age specific BMI cut-offs were used to define overweight and obesity. Underweight was defined as a BMI-for-age z-score <-2, based on the US Centers for Disease Control and Prevention (CDC) 2000 growth reference. In 2002, students completed a questionnaire about household assets. In 2004, parents answered questions about their weight, height, education, occupation, and ownership of 14 household assets. RESULTS: The prevalence of overweight and obesity increased from 5.0% and 0.6% in 2002, to 11.7% and 2.0% in 2004, respectively (p<0.001), while the prevalence of underweight decreased from 13.1% to 6.7%. There was a significant increase in prevalence of overweight and obesity by gender over the two years: the 113% increase in prevalence of overweight and obesity in boys was significantly greater than the 39% increase in girls (p<0.001). The percentage increase in overweight and obesity was considerably lower in adolescents from the poorest households (33%), than from the other quintiles of wealthier households (ranging from 77% to 124%) (p<0.001). CONCLUSIONS: The prevalence of overweight and obesity among adolescents in Ho Chi Minh City is increasing rapidly. There is an urgent need to implement strategies for prevention and control amongst the adolescents of Ho Chi Minh City and other urban areas in Vietnam.