Asthma. Definition and clinical spectrum.

When variability and periodicity of symptoms and of airway function are accompanied by evidence of an allergic pathogenesis (identified inhalant precipitants, atopy, raised IgE, eosinophilia) the diagnosis of asthma is obvious to patient and physician. But many patients with asthma do not conform to this classic stereotype, so that considerable problems of distinction from other types of airway obstruction exist. These difficulties have practical significance because conferring the label of asthma is associated with physicians prescribing more intensive and effective treatment.