Do measures of bronchial responsiveness add information in diagnosis and monitoring of patients with asthma?

Intermittent airflow limitation, bronchial hyperresponsiveness (BHR), airway inflammation and remodelling are key pathophysiological components of bronchial asthma [1]. BHR, an abnormal increase in airflow limitation following exposure to a stimulus, is present in almost all patients with clinically current asthma. Furthermore, patients with more severe asthma have more responsive airways than patients with mild disease and during exacerbations of asthma, for example during allergen exposure, increases in bronchial responsiveness do occur [2]. The measurement of bronchial responsiveness is widely available, well-standardized and can be applied in both research and clinical settings [3, 4]. Until recently, the evaluation of airway inflammation required bronchoscopy for taking bronchial biopsies and/or performing bronchoalveolar lavage (BAL). In recent years, noninvasive methods for the evaluation of airway inflammation have been developed: induced sputum and exhaled air are now increasingly applied in clinical studies and are becoming well-standardized tools that may also find application in the clinical setting [5–7].