Body mass index of Vietnamese children ages 6--15 years old

Childhood overweight can increase the risk of chronic diseases later in life. To determine the prevalence, trends and determinants of overweight among children ages 6-15 years old in Vietnam, we assessed data on body mass index (BMI) and demographic and socio-economic characteristics obtained from the 1992 Vietnam Living Standard Survey (1992 VLSS), the 1997 Vietnam Living Standard Survey (1997 VLSS), and the 2000 General Nutrition Survey (2000 GNS). These surveys used multi-stage cluster sample designs to produce nationally representative samples of Vietnamese children ages 6-15 years in 1992-1993, 1997-1998 and 2000. BMI classification was determined using cut-off values set by the International Obesity Task Force (IOTF). The mean prevalence of at risk of overweight and overweight among Vietnamese children rapidly increased from 0.4% in 1992 to 2.0% in 2000, along with a high prevalence of underweight (33.4% in 2000). Increases in weight, height and BMI varied according to gender, area of residence and socioeconomic status. Age, areas of residence and education of the household head are statistically significant predictors of at risk of overweight and overweight. This study identified the prevalence and trends of weight among children crucial to understanding the prevention of child overweight in Vietnam. ^

Body mass index trajectories and predictors among 3rd to 12th graders using growth curve mixture modeling the Child and Adolescent Trial for Cardiovascular Health (CATCH) study

This dissertation examined body mass index (BMI) growth trajectories and the effects of gender, ethnicity, dietary intake, and physical activity (PA) on BMI growth trajectories among 3rd to 12th graders (9-18 years of age). Growth curve model analysis was performed using data from The Child and Adolescent Trial for Cardiovascular Health (CATCH) study. The study population included 2909 students who were followed up from grades 3-12. The main outcome was BMI at grades 3, 4, 5, 8, and 12. ^ The results revealed that BMI growth differed across two distinct developmental periods of childhood and adolescence. Rate of BMI growth was faster in middle childhood (9-11 years old or 3rd - 5th grades) than in adolescence (11-18 years old or 5th - 12th grades). Students with higher BMI at 3rd grade (baseline) had faster rates of BMI growth. Three groups of students with distinct BMI growth trajectories were identified: high, average, and low. ^ Black and Hispanic children were more likely to be in the groups with higher baseline BMI and faster rates of BMI growth over time. The effects of gender or ethnicity on BMI growth differed across the three groups. The effects of ethnicity on BMI growth were weakened as the children aged. The effects of gender on BMI growth were attenuated in the groups with a large proportion of black and Hispanic children, i.e., “high” or “average” BMI trajectory group. After controlling for gender, ethnicity, and age at baseline, in the “high BMI trajectory”, rate of yearly BMI growth in middle childhood increased 0.102 for every 500 Kcals increase (p=0.049). No significant effects of percentage of energy from total fat and saturated fat on BMI growth were found. Baseline BMI increased 0.041 for every 30 minutes increased in moderate-to-vigorous PA (MVPA) in the “low BMI trajectory”, while Baseline BMI decreased 0.345 for every 30 minutes increased in vigorous PA (VPA) in the “high BMI trajectory”. ^ Childhood overweight and obesity interventions should start at the earliest possible ages, prior to 3rd grade and continue through grade school. Interventions should focus on all children, but specifically black and Hispanic children, who are more likely to be highest at-risk. Promoting VPA earlier in childhood is important for preventing overweight and obesity among children and adolescents. Interventions should target total energy intake, rather than only percentage of energy from total fat or saturated fat. ^