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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #330864
Title: Obesity status trajectory groups among elementary school children

Author
item CHEN, TZU - University Of Texas Health Science Center
item BARANOWSKI, TOM - Children'S Nutrition Research Center (CNRC)
item MORENO, JENNETTE - Children'S Nutrition Research Center (CNRC)
item O'CONNOR, TERESIA - Children'S Nutrition Research Center (CNRC)
item HUGHES, SHERYL - Children'S Nutrition Research Center (CNRC)
item BARANOWSKI, JANICE - Children'S Nutrition Research Center (CNRC)
item WOEHLER, DEBORAH - The Cluthe And William B Oliver Foundation
item KIMBRO, RACHEL - Rice University
item JOHNSTON, CRAIG - University Of Houston

Submitted to: BioMed Central(BMC) Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2016
Publication Date: 7/7/2016
Citation: Chen, T.A., Baranowski, T., Moreno, J.P., O'Connor, T.M., Hughes, S.O., Baranowski, J., Woehler, D., Kimbro, R.T., Johnston, C.A. 2016. Obesity status trajectory groups among elementary school children. BioMed Central(BMC) Public Health. 16:526.

Interpretive Summary: While the probability of becoming overweight or obese increases throughout the elementary school years, it is not clear if there is a gradual increase in this risk for everyone or are there subgroups who are more likely to experience increased risk at specific times. We analyzed data with body mass indices on 1651 elementary school children from kindergarten to the beginning of 5th grade using a longitudinal cluster analysis method. This procedure identified that most children were consistently healthy weight (about 50%) or consistently overweight (about 20%). One group of children (about 10%) increased their risk of becoming overweight or obese starting at the end of kindergarten, and another (also about 10%) increased their risk at the end of 2nd grade. Boys, Hispanic and non-Hispanic Black children were more likely to be in the groups experiencing increased risks. The next step in this line of research should be to identify what behaviors and environmental influences lead to this increased risk, in order to develop precise targeted interventions.

Technical Abstract: Little is known about patterns in the transition from healthy weight to overweight or obesity during the elementary school years. This study examined whether there were distinct body mass index (BMI) trajectory groups among elementary school children, and predictors of trajectory group membership. This is a secondary analysis of 1651 elementary school children with complete biannual longitudinal data from kindergarten to the beginning of 5th grade. Heights and weights were measured by trained school nurses using standard procedures at the beginning and end of each school year for 11 consecutive assessments. Group-based trajectory clustering and multinomial logit modeling were conducted. When using BMIz score, six trajectory groups were identified revealing substantial consistency in BMIz score across time. When using a categorical variable separating overweight/obese children (BMI >=85%ile) from the rest, five developmental trajectories (persistently non-overweight/obese weight: 51.1%; early-onset overweight/obese: 9.2%; late-onset overweight/obese: 9.7%; becoming healthy weight: 8.2%; and chronically overweight/obese: 21.8%) were identified. When using a categorical variable separating obese children (BMI >=95%ile) from the rest, three trajectories (persistently non-obese: 74.1%, becoming obese: 12.8%; and chronically obese: 13.2%) were identified. For both cutoffs (= BMI percentile 85% or 95%), girls were more likely than boys to be classified in the persistently non-overweight and/or obese group (odds ratios (OR) ranged from 0.53 to 0.67); and Hispanic children and non-Hispanic Black children were more likely to be chronically overweight and/or obese than non-Hispanic White children (OR ranged from 1.57 to 2.44). Hispanic children were also more likely to become obese (OR: 1.84) than non-Hispanic White children when >=BMI percentile 95% was used. Boys, Hispanic and non-Hispanic Black children were at higher risk of being overweight or obese throughout their elementary school years, supporting the need for obesity treatment. Post kindergarten and post second grade summer months were times when some children transitioned into overweight/obesity. It will be important to identify which behavioral factors (e.g., diet, physical activity, sedentary behaviors, and/or sleep) predisposed children to becoming overweight/obese, and whether these factors differ by time (Kindergarten versus second grade). If behavioral predisposing factors could be identified early, targeted obesity prevention should be offered.