Categorizing asthma severity and monitoring control of chronic asthma.

Asthma is a distressing disease, affecting up to 8% of the US population and causing considerable morbidity. Effective management of asthma requires accurate categorization of asthma severity and effective methods for monitoring the activity of the disease with treatment. Currently, symptoms, lung function, and requirements for corticosteroid treatment are the most accepted factors used for asthma severity categorization. Measures of airway hyperresponsiveness, particularly the use of methacholine, may provide additional information regarding the duration of asthma. Assessing airway inflammation using either sputum eosinophilia or exhaled nitric oxide levels has added little to clinical methods for determining asthma severity, but may be useful in monitoring the activity of the disease.