Asthma is a respiratory disease involving the bronchial tubes, which carry air from the windpipe to the tiny air sacs in the lungs. When a person has asthma, the bronchial tubes are inflamed, hyperactive and are clogged with mucus. A variety of triggers can cause these tubes to go into spasms, called asthma attacks or episodes. These attacks leave the person with asthma gasping for breath. However, symptoms vary with individuals.
Diagnosis of asthma can be difficult, particularly in the very old or very young.
In addition, asthma or asthma-related symptoms vary in individuals. There is also difficulty with comparing various databases. For these reasons, we must qualify all estimates regarding the prevalence and severity of asthma. We focused on gathering together the available information in a format that is as consistent as possible. In addition to prevalence and mortality measures, asthma can be tracked by using health care utilization data.