title: What can providers learn from childhood body mass index trajectories: a study of a large, safety-net clinical population.
abstract: OBJECTIVE
  To describe childhood weight gain using body mass index (BMI) z-score trajectories in a low-income urban safety-net population and identify among gender- and race/ethnicity-specific groups any trends for increased risk.
  
  
  METHODS
  A retrospective cohort study was conducted among 2- to 12-year-old patients (2006-2013) visiting a safety-net provider. BMI z-score trajectories were calculated overall, for gender- and race/ethnicity-specific groups, and for peak BMI percentile subgroups to describe weight gain longitudinally.
  
  
  RESULTS
  From 2006 to 2013, a total of 26,234 eligible children were followed for an average of 3.7 years. At baseline (mean age, 4.2 years), 74% of patients were at a normal weight compared to 65% at most recent observation (mean age, 7.8 years). All gender and race/ethnicity subgroups showed increasing average BMI z-scores during childhood. Children consistently under the 50th percentile and those of white race had the most stable BMI z-score trajectories. BMI z-score increased with increasing age in all subgroups. Hispanic boys and black girls had the most significant increase in BMI z-score during this observation period. Children observed in early childhood and whose BMI exceeded the 95th percentile at any time were often already overweight (20%) or obese (36%) by 3 years of age.
  
  
  CONCLUSIONS
  The entire population demonstrated an upward trend in BMI z-score trajectory. This trend was most notable among black girls and Hispanic boys. Many obese children were already overweight by age 3, and persistence of obesity after 3 years of age was high, suggesting that intervention before age 3 may be essential to curbing unhealthy weight trajectories.
authors.affiliation: Denver Public Health, Denver Health, Denver, Colo. Electronic address: Emily.mccormick@dhha.org.
authors.forename: Emily V
authors.initials: EV
authors.lastname: McCormick
authors.affiliation: Department of Biostatistics and Informatics and Family Medicine, University of Colorado, Aurora, Colo.
authors.forename: L Miriam
authors.initials: LM
authors.lastname: Dickinson
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colo.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Haemer
authors.affiliation: Division of General Pediatrics, Community Health Services, Denver Health, Denver, Colo.
authors.forename: Shanna D
authors.initials: SD
authors.lastname: Knierim
authors.affiliation: Department of Pediatrics, University of Colorado, Aurora, Colo; Department of Epidemiology, University of Colorado, Aurora, Colo; Division of General Pediatrics, Community Health Services, Denver Health, Denver, Colo.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Hambidge
authors.affiliation: Denver Public Health, Denver Health, Denver, Colo; Department of Biostatistics and Informatics and Family Medicine, University of Colorado, Aurora, Colo; Department of Pediatrics, University of Colorado, Aurora, Colo.
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Davidson
mesh_terms: D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003120:Colorado / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D063766:Pediatric Obesity / Q000453:epidemiology* / Q000208:ethnology / Q000517:prevention & control; D011159:Population Surveillance; D015995:Prevalence; D012189:Retrospective Studies
keywords: BMI; obesity; prevention; trajectory