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.

Validity and reliability of a physical activity questionnaire for Vietnamese adolescents.

BACKGROUND: Accurate assessment of physical activity in adolescents at population level is necessary. In Vietnam, the International Physical Activity Questionnaire (IPAQ) and Physical Activity Questionnaire for Adolescents (PAQA) have been validated against accelerometers for use in adolescents. However, these questionnaires were originally designed for adults and showed poor validity. This study aims to assess the reliability and validity of the Vietnamese Adolescent Physical Activity Recall Questionnaire (V-APARQ). METHODS: One hundred and sixty five students were recruited from four junior high schools in Ho Chi Minh City Vietnam in 2004. V-APARQ asked students to report their usual organised and non-organised physical activity during a normal week and moderate- (MPA), vigorous- (VPA and moderate-to-vigorous- (MVPA) physical activity were calculated. Reliability was assessed by test-retest (2 weeks apart). Construct validity was assess by 7-day accelerometry, following the completion of the first V-APARQ. RESULTS: The construct validity of the V-APARQ showed Spearman correlation of 0.25 and 0.22 for the assessment of the questionnaire when compared to the accelerometer. Test-retest reliability showed a weighted Kappa of 0.75 and the intra-class correlation coefficient for MVPA was 0.57 for the whole group (MPA =0.37 and VPA = 0.62), and were higher in boys than girls. The Bland-Altman plots for reliability show a mean difference of 0.4 minutes (95 % CI = -3.2, 4.0) for daily MVPA (n = 146) and the limits of agreement were -42.6 to 43.4 mins/day. In boys MVPA was lower on the first, compared with second administration of V-APARQ while the reverse was observed among girls. CONCLUSION: The reliability and validity of the V-APARQ were low to fair, but are comparable to other self-report physical activity questionnaires used among adolescents. V-APARQ will be useful for population monitoring of change in physical activity among urban Vietnamese adolescents.

Active commuting to school among adolescents in Ho Chi Minh City, Vietnam: change and predictors in a longitudinal study, 2004 to 2009.

BACKGROUND: Active commuting (walking or cycling) to/from school is an important part of the overall physical activity levels of children but is on the decline in many countries. Data for adolescents on mode of transportation to and from school are limited for low- and middle-income countries, including Vietnam. PURPOSE: This paper aims to describe the changes in the prevalence of active commuting to and from school, and to examine prospectively the predictors of active commuting, among adolescents from Ho Chi Minh City (HCMC). METHODS: The data are from a 5-year cohort study from 2004 of a representative sample of 759 adolescents from 18 schools in HCMC. Data were obtained at five annual assessments using validated questionnaires to capture commuting behaviors, socioeconomic and demographic factors, individual and family characteristics, and physical and social environmental factors. Height and weight were measured by trained staff using standardized guidelines. Generalized linear latent and mixed models with a hierarchic approach were used to analyze the data in 2011. RESULTS: The results show a remarkable decrease in the prevalence of active commuting in adolescents from 27.8% in 2004 to 19.6% in 2009. Male students, from the least-wealthy families, living in suburban areas, close to school, studying at schools in less-wealthy districts, were more likely to actively commute. CONCLUSIONS: In the context of an epidemic of childhood and adolescent obesity in urban Vietnam, the decline in active commuting over the 5 years of this study highlights the need for development of urban physical environments favorable for active commuting and education campaigns to promote active commuting in adolescents.

Validity and reliability of an FFQ for use with adolescents in Ho Chi Minh City, Vietnam.

OBJECTIVE: The present study evaluates the reliability and validity of an FFQ designed for use with adolescents in urban Vietnam. DESIGN: A cohort study was conducted between December 2003 and June 2004. The FFQ was administered three times over a 6-month period (FFQ 1-3) and nutrient intakes were compared to those obtained from four 24 h recalls collected over the same period (24 h recalls 1-4) using crude, energy-adjusted and de-attenuated correlation coefficients. The level of agreement between the two measurements was also evaluated with Bland-Altman analysis. The percentage of nutrient intakes classified within one quintile, as well as quadratic-weighted kappa statistics, were calculated. SETTING: Ho Chi Minh City, Vietnam. SUBJECTS: A total of 180 students were recruited in three junior high schools. RESULTS: Coefficients ranged from 0.22 for retinol to 0.78 for fibre for short-term reliability, and from 0.30 for retinol to 0.81 for zinc for long-term reliability. Coefficients for nutrient intakes between the mean of the three FFQ and mean of four 24 h recalls were mostly around 0.40, but higher for energy-adjusted nutrients. After allowing for within-person variation, the mean coefficient was 0.52 for macronutrients and 0.46 for micronutrients. There were a relatively high proportion of nutrient intakes classified within one quintile and a small number grossly misclassified. Kappa values shows 'fair' to 'good' agreement for all food/nutrient categories, while the Bland-Altman plots indicated that the FFQ is accurate in assessing nutrient intake at a group level. CONCLUSIONS: This newly developed FFQ is a valid tool for measuring nutrient intake in adolescents in urban Vietnam.

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.