Bronchial hyperresponsiveness in children and adolescents

Area of Science:

• Pulmonary Medicine
• Pediatric Pulmonology
• Epidemiology

Background:

• Bronchial hyperresponsiveness (BHR) is a key feature in asthma, but its prevalence and implications in pediatric populations require further investigation.
• Understanding the distribution and triggers of BHR is crucial for accurate diagnosis and management of respiratory conditions in children and adolescents.

Purpose of the Study:

• To investigate the frequency distribution of bronchial responsiveness to inhaled histamine and exercise in children and adolescents.
• To explore the relationship between BHR, asthma symptoms, atopy, and lung function changes over time.
• To evaluate the utility of bronchial challenge tests in epidemiologic studies of asthma.

Main Methods:

• Assessed bronchial responsiveness using inhaled histamine (PC20) and exercise challenge (delta % FEV1) in a population sample of children and adolescents.
• Analyzed the frequency distributions of BHR and its association with asthma, atopy (house-dust mites, horse epithelium), viral infections, and smoke exposure.
• Followed subjects for 18 months to assess changes in lung function (FEV1) and height, and the development of asthma.

Main Results:

• BHR to histamine and/or exercise was found in 16% of the study population, with 6% exhibiting BHR to both stimuli.
• A significant but complex relationship was observed between responsiveness to histamine and exercise.
• While low positive predictive values (PVpos) suggest inadequacy for screening, high negative predictive values (PVneg) indicate bronchial challenges can exclude asthma.
• Asymptomatic BHR was associated with reduced lung function increase and potentially permanent lung impairment.
• BHR degree was influenced by asthma symptoms and atopy, but not by recent viral infection, smoke, or baseline lung function.

Conclusions:

• Bronchial hyperresponsiveness is frequently observed in pediatric populations and is closely related to asthma and atopy.
• Increased bronchial responsiveness in children and adolescents with BHR can persist and may lead to impaired lung function.
• Individuals who develop asthma often have pre-existing asymptomatic BHR, highlighting the importance of early identification.