title: Increased asymptomatic airway hyper-responsiveness in obese individuals.
abstract: OBJECTIVE
  Asymptomatic airway hyper-responsiveness (AHR) represents a risk of further accelerated decline in lung function, and of asthma. Due to the fact that rare and contradictory results exist concerning the impact of obesity on BHR, we re-assessed the prevalence of bronchial hyper-responsiveness (BHR) in a large cohort of 60 lean, 84 overweight, and 360 class 1-3 obese non-asthmatic individuals, by coupled plethysmography and spirometry.
  
  
  METHODS
  Baseline-specific airway conductance (SGaw) and spirometric values were measured and then a methacholine challenge testing (MCT) was performed and considered as positive when a ≥200% increase in specific airway resistance (SRaw = 1/SGaw) was reached.
  
  
  RESULTS
  Compared to lean and overweight subjects, obese subjects of any class presented about a twice more frequent AHR (∼ 50% in obese vs. 17 and 26% in lean and overweight subjects, respectively). However, the bronchial sensitivity (methacholine dose doubling SRaw) and the shape of the relationship between SGaw and cumulative methacholine doses were the same in the five groups of individuals.
  
  
  CONCLUSIONS
  The present data show a more frequent AHR in obese subjects. The association of plethysmography with spirometry, by taking into account the bronchodilator effect of the lung inflation (preceding the expiratory flow measurement) in some individuals, permitted to include some MCT which would have been otherwise excluded.
authors.affiliation: Explorations Fonctionnelles Respiratoires, Pôle thoracique et cardiovasculaire, Hôpital Nord. Chemin des Bourrely. 13915 Marseille Cedex 20, France.
authors.forename: Monique
authors.initials: M
authors.lastname: Badier
authors.forename: Chantal
authors.initials: C
authors.lastname: Guillot
authors.forename: Stéphane
authors.initials: S
authors.lastname: Delpierre
mesh_terms: D016535:Bronchial Hyperreactivity / Q000453:epidemiology* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology; D050177:Overweight / Q000453:epidemiology* / Q000503:physiopathology; D010991:Plethysmography; D015995:Prevalence; D013147:Spirometry
chemical_list: D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride