title: Obesity status transitions across the elementary years: use of Markov chain modelling.
abstract: OBJECTIVE
  The objective of this study was to assess overweight and obesity status transition probabilities using first-order Markov transition models applied to elementary school children.
  
  
  METHODS
  Complete longitudinal data across 11 assessments were available from 1494 elementary school children (from 7599 students in 41 out of 45 schools in a Southeast Texas school district) from kindergarten to the beginning of the fifth grade. Heights and weights were measured by trained school nurses using standard procedures at the beginning and end of each school year for the 11 consecutive assessments. To estimate the transition probabilities, first-order three-state (healthy weight, overweight and obese) Markov transition models were fit to the longitudinal weight status data of all assessment periods.
  
  
  RESULTS
  While there was a gradual shift to more children in the overweight or obese category over 5 years, children were most likely to stay in the same weight category as the previous assessment. A consistent seasonal difference in the probability of changing weight status category was seen, with a greater probability of becoming overweight and obese during the summer compared with the school year. The transition probabilities to obesity were higher among boys, Hispanic and non-Hispanic Black, and lower socioeconomic status children.
  
  
  CONCLUSIONS
  This study provides the first application of a Markov transition model to child weight status data. The transitions into the overweight and obese categories were small, but persistent, with smaller percentages transitioning out of overweight or obese. Early monitoring and summer intervention strategies are needed to prevent the slow, but relentless, transition into the overweight and obese categories.
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: T-A
authors: TA
authors: Chen
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: T
authors: T
authors: Baranowski
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: J P
authors: JP
authors: Moreno
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: T M
authors: TM
authors: O'Connor
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: S O
authors: SO
authors: Hughes
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
authors: J
authors: J
authors: Baranowski
authors: The Oliver Foundation, Houston, Texas, USA.
authors: D
authors: D
authors: Woehler
authors: Department of Sociology, Rice University, Houston, Texas, USA.
authors: R T
authors: RT
authors: Kimbro
authors: USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.|Department of Medicine, Baylor College of Medicine, Houston, Texas, USA.
authors: C A
authors: CA
authors: Johnston
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008390:Markov Chains; D063766:Pediatric Obesity / Q000453:epidemiology / Q000517:prevention & control*; D012572:School Health Services / Q000458:organization & administration*; D012574:Schools; D013334:Students; D013781:Texas / Q000453:epidemiology; D015430:Weight Gain
keywords: Childhood obesity; Markov chain; longitudinal; weight gain