Small Airways Disease in Asymptomatic and Symptomatic Subjects With Airway Hyperresponsiveness (AHR)

Differences in Small Airways Disease Between Asymptomatic and Symptomatic Subjects With Airway Hyperresponsiveness

The purpose of this study is to study differences in small airways (<2mm) parameters in asthma patients, subjects with asymptomatic airway hyperresponsiveness and healthy controls.

Inclusion criteria for asymptomatic subjects with airway hyperresponsiveness (AHR) :

• Age between 18 and 65 years.
• Forced expiratory volume in one second (FEV1) > 80% predicted post bronchodilator.
• Provocative concentration causing a 205 fall in FEV1 (PC20) methacholine <8 mg/ml.
• No history of asthma or previous use of asthma medication.

Inclusion criteria for asymptomatic subjects without AHR :

• Age between 18 and 65 years.
• FEV1 > 80% predicted post bronchodilator.
• PC20 methacholine >8 mg/ml.
• No history of asthma or previous use of asthma medication.

Inclusion criteria for patients with asthma:

• Age between 18 and 65 years.
• FEV1 > 80% predicted.
• PC20 methacholine ≤8 mg/ml.
• Doctor's diagnosis of asthma.
• No history of Chronic obstructive pulmonary disease (COPD).

Exclusion Criteria:

• Use of inhaled or oral steroids, antihistamines, nedocromil, theophylline, leukotrien antagonists or long-acting beta-agonists for at least three weeks before the start of the study.
• Any disease that may affect the outcome of the study as judged by the Investigator.
• FEV1 <1.2 liter.