Less small airway dysfunction in asymptomatic bronchial hyperresponsiveness than in asthma

Allergy. 2013 Nov;68(11):1419-26. doi: 10.1111/all.12242. Epub 2013 Oct 12.


Background: Bronchial hyperresponsiveness (BHR) can be present in subjects without any respiratory symptoms. Little is known about the role of the small airways in asymptomatic subjects with BHR.

Methods: We investigated small airway function assessed by spirometry and impulse oscillometry, as well as Borg dyspnea scores at baseline and during a methacholine provocation test in 15 subjects with asymptomatic BHR, 15 asthma patients, and 15 healthy controls.

Results: At baseline, small airway function (R5 -R20 and X5 ) was comparable between subjects with asymptomatic BHR and healthy controls, whereas asthma patients showed small airway dysfunction as reflected by higher R5 -R20 and lower X5 values. During methacholine provocation, small airway dysfunction was more severe in asthma patients than in subjects with asymptomatic BHR. Interestingly, a higher increase in small airway dysfunction during methacholine provocation was associated with a higher increase in Borg dyspnea scores in subjects with asymptomatic BHR, but not in asthma patients.

Conclusion: Subjects with asymptomatic BHR may experience fewer symptoms in daily life because they have less small airway dysfunction.

Keywords: asthma; asymptomatic bronchial hyperresponsiveness; small airways.

Publication types

  • Comparative Study
  • Observational Study

MeSH terms

  • Adult
  • Asthma / epidemiology
  • Asthma / immunology*
  • Asthma / physiopathology*
  • Asymptomatic Diseases / epidemiology
  • Body Mass Index
  • Bronchial Hyperreactivity / epidemiology
  • Bronchial Hyperreactivity / immunology*
  • Bronchial Hyperreactivity / physiopathology*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Male
  • Methacholine Chloride / administration & dosage
  • Middle Aged
  • Pulmonary Disease, Chronic Obstructive / epidemiology
  • Randomized Controlled Trials as Topic / trends
  • Young Adult


  • Methacholine Chloride