Lack of correlation between bronchoconstrictor response and bronchodilator response in a population-based study

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology
• Epidemiology

Background:

• Bronchodilator and bronchoconstrictor responsiveness are traditionally viewed as opposing physiological states in obstructive airways disease.
• Bronchodilator testing has largely superseded provocation challenges in assessing severe airway obstruction.

Purpose of the Study:

• To investigate the relationship between bronchoconstrictor and bronchodilator responsiveness in a general population.
• To evaluate the interchangeability of these responsiveness measures in epidemiological research.

Main Methods:

• Recruited 101 adults from the Vlagtwedde-Vlaardingen follow-up study.
• Assessed bronchoconstrictor responsiveness using histamine dose-response curves (determining PC10 for a 10% fall in FEV1).
• Assessed bronchodilator responsiveness using terbutaline dose-response curves (determining maximal delta FEV1 and RD10 for a 10% increase in FEV1).

Main Results:

• Subjects with bronchoconstrictor response (PC10 ≤ 16 mg x mL⁻¹) reported more respiratory symptoms and had lower baseline FEV1, but similar bronchodilator responsiveness compared to those without.
• Subjects with a bronchodilator response (delta FEV1 ≥ 9% predicted) showed no significant differences in symptoms, allergy, or pulmonary function.
• A weak but significant negative correlation was found between histamine sensitivity (PC10) and terbutaline sensitivity (RD10) in subjects with bronchoconstrictor response, but not with maximal bronchodilator response (delta FEV1).

Conclusions:

• Bronchoconstrictor and bronchodilator responsiveness are not strongly correlated and are not interchangeable phenotypic markers.
• Respiratory symptoms are associated with bronchoconstrictor responsiveness, but not bronchodilator responsiveness.
• These distinct markers have different implications for epidemiological studies of respiratory health.