title: Growth curves of preschool children in the northeast of iran: a population based study using quantile regression approach.
abstract: BACKGROUND
  Growth charts are widely used to assess children's growth status and can provide a trajectory of growth during early important months of life. The objectives of this study are going to construct growth charts and normal values of weight-for-age for children aged 0 to 5 years using a powerful and applicable methodology. The results compare with the World Health Organization (WHO) references and semi-parametric LMS method of Cole and Green.
  
  
  METHODS
  A total of 70737 apparently healthy boys and girls aged 0 to 5 years were recruited in July 2004 for 20 days from those attending community clinics for routine health checks as a part of a national survey. Anthropometric measurements were done by trained health staff using WHO methodology. The nonparametric quantile regression method obtained by local constant kernel estimation of conditional quantiles curves using for estimation of curves and normal values.
  
  
  RESULTS
  The weight-for-age growth curves for boys and girls aged from 0 to 5 years were derived utilizing a population of children living in the northeast of Iran. The results were similar to the ones obtained by the semi-parametric LMS method in the same data. Among all age groups from 0 to 5 years, the median values of children's weight living in the northeast of Iran were lower than the corresponding values in WHO reference data. The weight curves of boys were higher than those of girls in all age groups.
  
  
  CONCLUSIONS
  The differences between growth patterns of children living in the northeast of Iran versus international ones necessitate using local and regional growth charts. International normal values may not properly recognize the populations at risk for growth problems in Iranian children. Quantile regression (QR) as a flexible method which doesn't require restricted assumptions, proposed for estimation reference curves and normal values.
authors.affiliation: Department of Biostatistics and Epidemiology, School of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
authors.forename: Abolfazl
authors.initials: A
authors.lastname: Payande
authors.forename: Hamed
authors.initials: H
authors.lastname: Tabesh
authors.forename: Mohammad Taghi
authors.initials: MT
authors.lastname: Shakeri
authors.forename: Azadeh
authors.initials: A
authors.lastname: Saki
authors.forename: Mohammad
authors.initials: M
authors.lastname: Safarian
mesh_terms: D000367:Age Factors; D001835:Body Weight / Q000502:physiology*; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D057238:Growth Charts; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007492:Iran; D008297:Male; D012016:Reference Values; D012044:Regression Analysis