title: Overweight, obesity, and incident asthma: a meta-analysis of prospective epidemiologic studies.
abstract: BACKGROUND
  Although obesity has been implicated as an asthma risk factor, there is heterogeneity in the published literature regarding its role in asthma incidence, particularly in men.
  
  
  OBJECTIVE
  To quantify the relationship between categories of body mass index (BMI) and incident asthma in adults and to evaluate the impact of sex on this relationship.
  
  
  METHODS
  Online bibliographic databases were searched for prospective studies evaluating BMI and incident asthma in adults. Independent observers extracted data regarding annualized asthma incidence from studies meeting predetermined criteria, within defined categories of normal weight (BMI < 25), overweight (BMI, 25-29.9), and obesity (BMI >or= 30). Data were analyzed by inverse-variance-weighted, random-effects meta-analysis. Stratified analysis between BMI categories and within sex was performed.
  
  
  RESULTS
  Seven studies (n=333,102 subjects) met inclusion criteria. Compared with normal weight, overweight and obesity (BMI >or= 25) conferred increased odds of incident asthma, with an odds ratio (OR) of 1.51 (95% confidence interval [CI], 1.27-1.80). A dose-response effect of elevated BMI on asthma incidence was observed; the OR for incident asthma for normal-weight versus overweight subjects was 1.38 (95% CI, 1.17-1.62) and was further elevated for normal weight versus obesity (OR, 1.92; 95% CI, 1.43-2.59; p<0.0001 for the trend). A similar increase in the OR of incident asthma due to overweight and obesity was observed in men (OR, 1.46; 95% CI, 1.05-2.02) and women (OR, 1.68; 95% CI, 1.45-1.94; p=0.232 for the comparison).
  
  
  CONCLUSIONS
  Overweight and obesity are associated with a dose-dependent increase in the odds of incident asthma in men and women, suggesting asthma incidence could be reduced by interventions targeting overweight and obesity.
authors.affiliation: Department of Medicine, National Jewish Medical and Research Center, 1400 Jackson Street, J220, Denver, CO 80206, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Beuther
authors.forename: E Rand
authors.initials: ER
authors.lastname: Sutherland
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D015992:Body Mass Index; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009765:Obesity / Q000150:complications*; D018570:Risk Assessment; D012737:Sex Factors