title: Development of cardiovascular risk factors from ages 8 to 18 in Project HeartBeat! Study design and patterns of change in plasma total cholesterol concentration.
abstract: BACKGROUND
  Project HeartBeat! is a longitudinal study of the development of cardiovascular risk factors as growth processes. Patterns of serial change, or trajectories, from ages 8 to 18 years for plasma total cholesterol concentration (TC) and percent body fat illustrate the design and synthetic cohort approach of the study.
  
  
  RESULTS
  Six hundred seventy-eight children (49.1% female, 20.1% black) entered the study at ages 8, 11, and 14 years and were followed up with examinations every 4 months for < or = 4 years. Multilevel analysis demonstrated trajectories for population mean values of TC and percent body fat in sex-specific synthetic cohorts from ages 8 to 18 years. Polyphasic patterns of change in TC were confirmed, with notable sex differences in age patterns and with minimum mean values of TC of 3.85 mmol/L for females and 3.59 for males. As illustrated by data for males, the approximate 75th percentile values of mean TC ranged from 4.78 mmol/L at its early peak to 4.06 at its late-teen nadir. Percent body fat exhibited a trajectory closely parallel with that for TC only for males and appeared to be unrelated for females.
  
  
  CONCLUSIONS
  The polyphasic trajectory for TC from ages 8 to 18 years differs between females and males, indicates marked age variation in 75th percentile values and, in males only, closely parallels the trajectory for percent body fat. These and other results indicate the value of both follow-up every 4 months across age intervals to detect rapid risk factor change and the synthetic cohort approach for gaining new insights into the dynamics and possible determinants of this change from ages 8 to 18 years.
authors.affiliation: University of Texas-Houston Health Science Center, School of Public Health 77030, USA. diabarthe@utsph.sph.uth.tmc.edu
authors.forename: D R
authors.initials: DR
authors.lastname: Labarthe
authors.forename: M Z
authors.initials: MZ
authors.lastname: Nichaman
authors.forename: R B
authors.initials: RB
authors.lastname: Harrist
authors.forename: J A
authors.initials: JA
authors.lastname: Grunbaum
authors.forename: S
authors.initials: S
authors.lastname: Dai
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000293:Adolescent; D000375:Aging / Q000097:blood*; D001823:Body Composition; D002318:Cardiovascular Diseases; D002648:Child; D002784:Cholesterol / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009994:Osmolar Concentration; D012307:Risk Factors; D012727:Sex Characteristics
chemical_list: D002784:Cholesterol