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Asymptomatic airway hyperresponsiveness: a three-year follow-up
1Unité de Recherche, Hôpital Laval, Université Laval, Sainte-Foy, Québec, Canada.
American Journal of Respiratory and Critical Care Medicine
|August 1, 1997
Summary
Asymptomatic airway hyperresponsiveness (AHR) increases over time and may lead to asthma symptoms. Genetic predisposition and allergen exposure are key risk factors for developing symptomatic asthma.
Area of Science:
- Pulmonology
- Immunology
- Allergy
Background:
- The clinical significance of asymptomatic airway hyperresponsiveness (AHR) remains unclear.
- Understanding AHR progression is crucial for asthma prevention.
Purpose of the Study:
- To investigate the longitudinal changes in AHR and the development of asthma symptoms.
- To identify risk factors associated with the progression from asymptomatic AHR to symptomatic asthma.
Main Methods:
- A 3-year longitudinal study comparing 30 asymptomatic AHR subjects, 30 symptomatic asthmatics, and 30 normoresponders.
- Utilized spirometry, bronchodilator response, peak expiratory flow variability, allergy skin tests, blood eosinophil counts, serum IgE, and methacholine challenges.
- Annual assessments were conducted to track physiological and immunological changes.
Main Results:
- Asymptomatic AHR subjects showed increased bronchodilator response, PEFR variability, and atopy compared to normoresponders.
- Compared to asthmatics, asymptomatic AHR subjects had lower eosinophils, higher FEV1, and greater perceived bronchoconstriction.
- Over 3 years, asymptomatic AHR subjects experienced a significant increase in airway responsiveness, with 14.3% developing asthma symptoms.
Conclusions:
- Asymptomatic AHR is associated with progressive airway hyperresponsiveness and an increased risk of developing asthma.
- Atopy, allergen exposure, and a family history of asthma are significant risk factors for symptomatic asthma development in individuals with AHR.