title: Sex differences in the relationship between asthma and overweight in Dutch children: a survey study.
abstract: OBJECTIVE
  Obesity has been identified as a risk factor for asthma in children. However, in the Netherlands, the obesity prevalence is rising while the asthma prevalence in children is stabilising. The aim of this study is to clarify the association between asthma and Body Mass Index (BMI) in children and whether this association is influenced by sex.
  
  
  METHODS
  Parents of 39,316 children (6-16 years) in the south of the Netherlands were invited to complete an online questionnaire on respiratory symptoms, anthropometric variables and several potential confounding factors for asthma and obesity (including sex, birth weight and breastfeeding). Data was analysed by multivariable logistic regression models and an ordinal regression model.
  
  
  RESULTS
  The response rate was 24% (n boys= 4,743, n girls= 4,529). The prevalence of asthma, overweight and obesity was 8%, 15% and 2% respectively. Body mass index--standard deviation Score (BMI-SDS) was related to current asthma (adjusted OR: 1.29; 95%CI: 1.14-1.45, p ≤ 0.001). When stratified for sex, asthma and BMI-SDS were only related in girls (Girls: adjusted OR: 1.31; 95%CI: 1.13-1.51, p ≤ 0.001. Boys: adjusted OR: 1.01; 95%CI: 0.91-1.14, p=0.72).
  
  
  CONCLUSIONS
  The positive association between BMI-SDS and asthma is only present in girls, not boys. Future studies into obesity and asthma should correct for sex in their analyses.
authors.affiliation: Department of Pediatric Respiratory Medicine, School for Public Health and Primary Care (CAPHRI), Maastricht University Medical Center (MUMC), Maastricht, The Netherlands.
authors.forename: Maartje
authors.initials: M
authors.lastname: Willeboordse
authors.forename: Donna L C M
authors.initials: DL
authors.lastname: van den Bersselaar
authors.forename: Kim D G
authors.initials: KD
authors.lastname: van de Kant
authors.forename: Jean W M
authors.initials: JW
authors.lastname: Muris
authors.forename: Onno C P
authors.initials: OC
authors.lastname: van Schayck
authors.forename: Edward
authors.initials: E
authors.lastname: Dompeling
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology*; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009426:Netherlands; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications*; D015995:Prevalence; D012307:Risk Factors; D012727:Sex Characteristics; D012737:Sex Factors; D011795:Surveys and Questionnaires