Conclusion: Airway hyperresponsiveness in asthma: its measurement and clinical significance.

or indirect challenges with inhaled mannitol 2 or exercise 3 is important in establishing a correct diagnosis. This is particularly true in excluding asthma as a diagnosis in patients with symptoms that suggest asthma, but are caused by another condition. This is because airway hyperresponsiveness measurements are very sensitive in determining a diagnosis of asthma (therefore, they have a high negative predictive value) but are not very specifi c because patients with other diseases, such as allergic rhinitis 4 or COPD, 5 can have airway hyperresponsiveness without asthma. This supplement to CHEST highlighted the many insights that have been made into the role of measuring both airway hyperresponsiveness and airway inflammation. These methods have proven very helpful clinically, as well as in mechanistic studies of asthma. The importance of airway infl ammation in increasing airway responsiveness after exposure to environmental or occupational stimuli, such as allergens, 6 or small-molecular-weight chemicals, such as toluene diisocyanate, 7 is now established; however, the role of airway infl ammation and its associated structural changes (airway remodeling) in initiating airway hyperresponsiveness remains unclear. Finally, the value of measuring both airway hyperresponsiveness and airway infl ammation in making treatment decisions, particularly about the doses of inhaled corticosteroids (ICS) used in patients, has been evaluated. Adjusting the doses of ICS to optimize the measurements of methacholine airway responsiveness leads to improved asthma control, 8