title: High screen time is associated with asthma in overweight Manitoba youth.
abstract: OBJECTIVE
  Low physical activity and high sedentary behavior are associated with adverse health outcomes, including asthma. The purposes were to (1) determine if low physical activity and/or high screen time increase the risk of asthma and airway hyperresponsiveness (AHR) in youth and (2) determine if weight status modifies these associations.
  
  
  METHODS
  This is a prospective cohort study of healthy weight and overweight Canadian youth. In 2003-2005, 723 youth (8.6 ± 0.5 years; 34.0% asthma, 55.9% boys) were recruited from the 1995 Manitoba Prospective Cohort Study. In 2008-2010, 489 returned for follow-up measures (30.9% asthma, 56.6% boys). The primary exposure variables were parent-reported physical activity and screen time at 8-10 years of age. The primary outcome measures were pediatric allergist-defined asthma and AHR defined as the provocative concentration of methacholine required to induce a 20% fall in forced expiratory volume in 1 second (FEV(1)).
  
  
  RESULTS
  Low physical activity (≤2 times weekly) was not associated with asthma or AHR. However, high screen time (≥1 hour/day) was associated with a greater odds of asthma at baseline (odds ratio (OR) = 2.01, 95% confidence interval (CI) = 1.20-3.37, p < .01) and follow-up (OR = 2.11, 95% CI = 1.14-3.89, p < .02) versus low screen time. This association was more pronounced among overweight youth (baseline: OR = 3.95, 95% CI = 1.70-9.12, p < .0001; follow-up: OR = 3.22, 95% CI = 1.17-8.86, p < .02). Screen time was not associated with AHR at baseline or follow-up.
  
  
  CONCLUSIONS
  High screen time increases the risk of asthma, particularly among overweight youth. Screen time, in addition to physical activity, should be included in clinical assessments of youth with asthma.
authors.affiliation: Department of Applied Health Sciences, University of Manitoba, Manitoba Institute of Child Health, Winnipeg, MB, Canada. jprotudjer@mich.ca
authors.forename: Jennifer
authors.initials: J
authors.lastname: Protudjer
authors.forename: Anita L
authors.initials: AL
authors.lastname: Kozyrskyj
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: McGavock
authors.forename: Clare D
authors.initials: CD
authors.lastname: Ramsey
authors.forename: Allan B
authors.initials: AB
authors.lastname: Becker
mesh_terms: D001249:Asthma / Q000453:epidemiology*; D001837:Body Weights and Measures; D016535:Bronchial Hyperreactivity / Q000453:epidemiology*; D002648:Child; D003201:Computers / Q000706:statistics & numerical data; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008350:Manitoba / Q000453:epidemiology; D050177:Overweight / Q000453:epidemiology*; D011446:Prospective Studies; D012111:Residence Characteristics; D012959:Socioeconomic Factors; D013690:Television / Q000706:statistics & numerical data