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Screen time among youth has been increasingly recognized as a public health problem because of its link with obesity. This has been demonstrated in many studies conducted in developed countries but few studies have addressed the problem in developing countries, despite an increase literature about the emergence of obesity and a greater access to screen devices in a country like Vietnam. Our study aimed at assessing screen time and its relationship with BMI in adolescents of Ho Chi Minh City (HCMC), Vietnam.In a cross-sectional study of 2024 junior high school students aged 11-14 of HCMC, students were measured for BMI and questioned on time spent watching television/Video/DVD or using computer for fun. High users were defined as time=2 h/d. International Obesity Task Force BMI cutoffs were used to define overweight and obesity.Adolescents spent 2.2 h/d in screen time, with higher values for boys than girls (p0.001). 53.8% of the respondents were high users. Time spent using computers for fun increased with age, and with the household wealthy index. The overall prevalence of overweight and obesity was 21.1%. Using multiple logistic regression, overweight and obesity was higher in boys (adjusted OR=2.66, 95% CI: [2.06; 3.44], p0.001) and in children aged 11-12 who had a screen time=2 h/d (adjusted OR=1.48, 95% CI: [1.09; 1.99], p0.02).In HCMC, a majority of adolescents spent=2 h/d on screen time. High screen time is associated with an increased prevalence of overweight and obesity in young adolescents. Public health intervention programs are needed to reduce screen time among youth.背景與目的：青少年在螢幕前花費的時間因與肥胖有著密切的關係而引起社 會的關注。多項研究只證明這個社會健康問題發生在發達國家。儘管肥胖的出 現和大量觀看螢幕設備相關的文獻不少，但有關這個問題的研究在越南等發展 中國家並不多。這項研究針對在越南胡志明市生活的青少年在螢幕前花費的時 間和他們體質指數之間的關係。方法與研究設計：對2024名11-14歲的初中生 進行橫斷面研究，測量學生的體質指數和詢問該名學生在螢幕前所花費的時 間，包括看電視與打電子遊戲。每日花費兩小時或以上的學生被定義為頻繁使 用者，並用國際肥胖工作組的臨界值定義超重和肥胖。結果：青少年每日在 螢幕前花費2.2小時，其中53.8%是頻繁使用者，而男生花費的時間比女生多 （p0.001）。學生的年齡越大和家庭財富越多，花費在電子遊戲的時間也隨 著增加。超重和肥胖總的流行率為21.1%。多元回歸結果發現，超重和肥胖的 學生中男生較多（調整後的OR=2.66, 95% CI：[2.06；3.44]，p0.001），而 11-12歲的兒童每日則在螢幕前花費兩小時或以上（調整後的OR=1.48, 95% CI：[1.09；1.99]，p0.02）。結論：在胡志明市，大部分青少年每日花費在螢 幕前的時間為兩小時或以上。青少年在螢幕前花費時間長與超重和肥胖流行率 增加有關。需要公共健康介入方案，以減少青少年在螢幕前花費的時間。.

Objective This study aimed to describe the prevalence of metabolic syndrome (MetS) in adolescents of Ho Chi Minh City (HCMC) and to identify components of cardiovascular risk clusters. Methods A cross-sectional study was conducted on a representative sample of 693 high-school students 13 to 16 years old in 2007. MetS was defined according to five different definitions: the Pediatric International Diabetes Federation, the Adult Treatment Panel III, and the modified definitions by Cook, Weiss, and De Ferranti. Principal components analysis (PCA) was carried out to cluster risk factors. Results The prevalence of MetS was high and varied from 3.9% to 12.5%, depending on the criteria used. High levels of triglycerides (or low High Density Lipoprotein Cholesterol) and high blood pressure were the most prevalent components of MetS, while impaired glucose tolerance was the least prevalent. PCA showed three factors in boys (obesity, hypertension, dyslipidemia) that cumulatively explained 64.3%, and four factors in females (obesity, hypertension, dyslipidemia, and hyperglycemia) that accounted for 73.6% of the observed variance of MetS. Conclusions The prevalence of MetS in HCMC adolescents was high. Obesity accounts for the maximum variance in clustering and appears to be a more powerful correlate of cardiovascular risk than other variables.

TRANG, N. H. H. D., T. K. HONG, H. P. VAN DER PLOEG, L. L. HARDY, P. J. KELLY, and M. J. DIBLEY. Longitudinal PhysicalActivity Changes in Adolescents: Ho Chi Minh City Youth Cohort. Med. Sci. Sports Exerc., Vol. 44, No. 8, pp. 1481–1489, 2012.Purpose: This study aimed to describe the 5-yr longitudinal change in moderate-to-vigorous physical activity (MVPA) among urbanadolescents in Ho Chi Minh City, Vietnam, and to identify individual, family, and environmental factors associated with changes inMVPA. Methods: The Ho Chi Minh City Youth Cohort is a 5-yr longitudinal cohort with systematic random sampling of 759 students(48% boys) from 18 junior high schools in Ho Chi Minh City, conducted from 2004 to 2009. All measures were taken on five separateoccassions. MVPA was assessed by self-report and accelerometry. Data were analyzed using multilevel linear regression models withestimation by generalized linear latent and mixed models. Results: Overall, after adjusting for covariates, students’ accelerometer-basedMVPA reduced 38% per annum (rate ratio = 0.62, 95% confidence interval (CI) = 0.59–0.64). Boys spent 2.9 times more in MVPA(rate ratio = 2.94, 95% CI = 2.63–3.22) than their female peers. Compared with normal-weight adolescents, overweight and obeseadolescents were doing 40% (rate ratio = 0.60, 95% CI = 0.53, 0.67) less MVPA. Conclusions: MVPA significantly declined amongVietnamese adolescents with age. This finding is similar to those reported among Western adolescents and suggests that strategiesto promote physical activity in adolescents are a priority in Vietnam because economic transitioning potentially increases the risk ofadopting unhealthy lifestyle behaviors associated with obesity and chronic diseases. Key Words: MODERATE-TO-VIGOROUSPHYSICAL ACTIVITY, ACCELEROMETER, ADOLESCENT PHYSICAL ACTIVITY RECALL QUESTIONNAIRE, COHORTSTUDY, CORRELATE, VIETNAM

To identify factors associated with overweight/obesity among adolescents in Ho Chi Minh City, Vietnam.In 2004, a cross-sectional survey was conducted using multi-stage cluster sampling. Weight and height of 2 678 students from 31 junior high schools in Ho Chi Minh City were measured. Dietary intake and physical activity were assessed using a validated food frequency questionnaire and a physical activity questionnaire. Parental, household and neighbourhood characteristics were also collected. Factors associated with overweight/obesity in adolescents were modelled using hierarchical, multivariate logistic regression. "Survey commands" in STATA were used to account for the multi-stage cluster sampling design.After adjusting for other study factors, the odds of overweight/obesity was significantly higher for male gender (OR=3.1, 95% CI: 1.8, 3.8), younger age (OR=3.4, 95% CI: 2.1, 5.3), schools located in wealthy districts (OR=2.5, 95% CI: 1.8, 3.4), higher family economic status (OR=1.9, 95% CI: 1.1, 4.9), higher parental education (OR=2.0, 95% CI: 1.4, 2.9), overweight or obese parents (OR=3.5, 95% CI: 1.7, 7.0), more time spent watching TV (OR=4.3, 95% CI: 1.3, 14.7), frequent consumption of soft drinks (OR=3.0, 95% CI: 1.6, 5.3) and more time studying after class (OR=2.9, 95% CI: 1.7, 4.9). The odds of overweight/obesity was lower with the availability of fruit at home (OR=0.5, 95% CI: 0.3, 0.7), frequent consumption of fruit/vegetables (OR=0.3, 95% CI: 0.2, 0.4) and being physically active (OR=0.5, 95% CI: 0.4, 0.8).Family/parental factors as well as children's lifestyle should be taken into account when planning interventions to prevent adolescent obesity.

To examine the use of health services for the treatment of childhood diarrhea in three southern provinces of Vietnam, and identified household, maternal, child and health service characteristics associated with this use, a cross-sectional household survey was conducted between November 1998 and January 1999. Women with a pre-school aged child living at home were the primary respondents for the survey questionnaires. Respondents were asked to recall diarrheal disease events experienced by their child during the two weeks prior to interview, and their responses to these events. Prevalence ratios (PR) were used to identify associations between maternal age, education, occupation, ethnicity, knowledge about diarrhea, feeding practises during diarrhea, household residence and economic status, disease severity, use of oral rehydration solution (ORS), time to nearest health care facility and overall satisfaction with local medical services, and the use of health care services for children ill with diarrhea. The two-week period prevalence of childhood diarrhea was 10% and varied by the province and ethnicity of the child's mother. Forty-three percent of mothers reported using ORS during diarrheal episodes. Seventy percent of mothers sought advice or treatment when their child became ill with diarrhea. After controlling for potential confounders in regression models, maternal ethnicity, maternal high school education (in comparison to no education or incomplete primary education), more severe disease and the use of ORS were factors associated with increased utilization of health care services. There was a low level of the utilization of ORS to treat children with diarrhea, especially by ethnic minority mothers. A high percentage of mothers reported low levels of satisfaction with medical services, especially those from ethnic minorities. Mothers from ethnic minorities and those with lower levels of education were less likely to seek advice or treatment. These findings suggest the need for programs to promote the use of ORS and use of appropriate services for the treatment of childhood diarrheal disease. Interventions are needed to improve the access of ethnic minority children to child health care services for the treatment of diarrhea.

Background: Two previous surveys conducted in Ho Chi Minh City revealed an increasing prevalence of overweight and obese adolescents, from 5.9% in 2002 to 11.7% in 2004. From 2004 to 2010, the government set up and implemented health promotion programs to promote physical activity and good nutritional habits in order to prevent overweight and obesity in children and adolescents. Our study aimed to estimate the prevalence of overweight and obesity among adolescents in urban areas of Ho Chi Minh City in 2010. Methods. A representative sample of 1,989 students aged 11-14 years was selected using a multistage cluster sampling method. 23 schools were randomly selected from the full list of all public junior high schools. In each selected school, 2 classes were chosen at random and all students from the class were examined. Age- and sex-adjusted overweight and obesity were defined using International Obesity Taskforce cut-offs. Results: The prevalences of overweight and obesity were 17.8% and 3.2%, respectively. Prevalences of overweight and obesity were significantly higher in boys (22%, 5.4%) than in girls (13.3%, 1.3%, p

Objectives The Ho Chi Minh Youth cohort study aimed to assess the change in nutritional status; indicators of adiposity; diet; physical activity and sedentary behaviours; home, neighbourhood and school microenvironments and their complex relationships in adolescents in urban areas of Ho Chi Minh City. Design Prospective 5-year cohort. Setting Systematic random sampling was used to select 18 schools in urban districts. Participants Children were followed up over 5 years with an assessment in each year. Consent, from both adolescents and their parents, was required. At baseline, 759 students were recruited into the cohort, and of these students, 740 remained in the cohort for the first round, 712 for the second round, 630 for the third round and 585 for the last round of follow-up. Primary and secondary outcome measures Anthropometric measurements were taken using established guidelines. Six main groups of exposure factors including dietary intake and behaviours, physical activity and sedentary behaviours, family social and physical environment, school environment, socioeconomic status and parental characteristics were measured. Results Retention rate was high (77%). Within 5-year period, the prevalence of combined overweight and obesity using International Obesity Task Force cut-off values increased from 14.2% to 21.8%. Time spent on physical activity decreased significantly in the 5-year period from 87 to 50 min/day. Time spent on sedentary behaviours increased in the 5-year period from 512 to 600 min/day. Conclusions The complete data analysis of this cohort study will allow a full exploration of the role of environmental and lifestyle behaviours on adolescent overweight and obesity and also identify the factors most strongly associated with excess weight gain and the appearance of overweight and obesity in different age groups of adolescents from this large city in Vietnam., Article summary Article focus The change in nutritional status; indicators of adiposity; diet; physical activity and sedentary behaviours; home, neighbourhood and school microenvironments and their complex relationships in adolescents in urban areas of Ho Chi Minh city. Key messages Prevalence of combined overweight/obesity increased from 14.2% to 21.8% in 5-year period. Time spent on physical activity decreased significantly in the 5-year period from 87 to 50 min/day. Time spent on sedentary behaviours increased in the 5-year period from 512 to 600 min/day. Strengths and limitations of this study This is the first cohort in Vietnam on adolescent obesity. This study assessed a full set of potential risk factors from dietary intake, physical activity and sedentary behaviours to environmental factors, allowing a wide ranging assessment of the factors related to excess weight gain and overweight and obesity among urban Vietnamese adolescents. The present longitudinal study revealed changes in anthropometric measurements, physical activity, sedentary behaviour and diet associated with age in both genders.