title: Increasing body mass index z-score is continuously associated with complications of overweight in children, even in the healthy weight range.
abstract: BACKGROUND
  Overweight/obesity in children is increasing. Incidence data for medical complications use arbitrary cutoff values for categories of overweight and obesity. Continuous relationships are seldom reported.
  
  
  OBJECTIVE
  The objective of this study is to report relationships of child body mass index (BMI) z-score as a continuous variable with the medical complications of overweight.
  
  
  METHODS
  This study is a part of the larger, prospective cohort Growth and Development Study.
  
  
  METHODS
  Children were recruited from the community through randomly selected primary schools. Overweight children seeking treatment were recruited through tertiary centers.
  
  
  METHODS
  Children aged 6-13 yr were community-recruited normal weight (n = 73), community-recruited overweight (n = 53), and overweight treatment-seeking (n = 51). Medical history, family history, and symptoms of complications of overweight were collected by interview, and physical examination was performed. Investigations included oral glucose tolerance tests, fasting lipids, and liver function tests.
  
  
  METHODS
  Adjusted regression was used to model each complication of obesity with age- and sex-specific child BMI z-scores entered as a continuous dependent variable.
  
  
  RESULTS
  Adjusted logistic regression showed the proportion of children with musculoskeletal pain, obstructive sleep apnea symptoms, headaches, depression, anxiety, bullying, and acanthosis nigricans increased with child BMI z-score. Adjusted linear regression showed BMI z-score was significantly related to systolic and diastolic blood pressure, insulin during oral glucose tolerance test, total cholesterol, high-density lipoprotein, triglycerides, and alanine aminotransferase.
  
  
  CONCLUSIONS
  Child's BMI z-score is independently related to complications of overweight and obesity in a linear or curvilinear fashion. Children's risks of most complications increase across the entire range of BMI values and are not defined by thresholds.
authors.affiliation: Telethon Institute for Child Health Research, Center for Child Health Research, University of Western Australia, Australia.
authors.forename: Lana M
authors.initials: LM
authors.lastname: Bell
authors.forename: Sue
authors.initials: S
authors.lastname: Byrne
authors.forename: Alisha
authors.initials: A
authors.lastname: Thompson
authors.forename: Nirubasini
authors.initials: N
authors.lastname: Ratnam
authors.forename: Eve
authors.initials: E
authors.lastname: Blair
authors.forename: Max
authors.initials: M
authors.lastname: Bulsara
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Jones
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Davis
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002657:Child Development; D015897:Comorbidity; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D009765:Obesity / Q000150:complications* / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors