Asthma is a chronic inflammatory disease, characterized by bronchial hyperresponsiveness and a variable, reversible airway obstruction. Despite improved diagnostics and therapy, asthma prevalence and mortality are increasing worldwide. Around 300 million people of all age groups and from all countries are suffering from asthma, making it a serious, global health-related problem.
Asthma leads to impairment in quality of life that correlates well with severity of disease. Times of absence from work and school may lead to social impairment. Patients with severe asthma have more frequent exacerbations, unscheduled physician and emergency visits. It is estimated, that a total number of 250.000 people worldwide die prematurely because of asthma.
There are several underlying factors that define the different asthma phenotypes. Therefore it is reasonable to understand asthma not as a single entity, but as a syndrome that comprises different pathologies which may in fact overlap in clinical practice. The different grading systems (e.g. severity, asthma control, intrinsic vs. extrinsic, dominating pattern of inflammation) reflect this diversity. In the past years it was proposed to reconsider the concept of asthma and to classify the disease according to the dominant phenotype. This approach not only needs a clinical and functional assessment, but also an evaluation that thoroughly assesses all aspects of asthma including pathophysiology, allergies, cellular and molecular diagnostics, thus providing the basis of a successful management of severe asthma.