Adult-onset eosinophilic asthma

In the last decades, it has been recognized that asthma is not a single disease, but comprises several clinical syndromes, which all share respiratory symptoms and lung function abnormalities, associated with different types of airway inflammation. These syndromes are now known as different asthma phenotypes. By far the best known phenotype consists of patients with childhood asthma, which is often mild and related to atopy. Patients with adult-onset asthma however, have a less common asthma phenotype with often more severe disease, with faster lung function decline, more persistent airflow limitation and less association with atopy. Most patients with asthma exhibit some degree of airway inflammation. The type and intensity of this airway inflammation can vary between different asthma subtypes. Eosinophilia, especially eosinophilic airway inflammation despite corticosteroid treatment, is associated with more severe disease with lung function abnormalities. This thesis is focused on different phenotypes of asthma and especially on the adult-onset, eosinophilic asthma phenotype, because of the possible high level of severity and the upcoming treatment options in eosinophilic asthma.
We established a cohort of 186 adult-onset asthma patients, to investigate clinical, functional and inflammatory characteristics of this specific subtype of asthma. The patients in our cohort were combined with two other adult-onset asthma cohorts. This enabled us to answer questions about different asthma subphenotypes with more power. The main focus became the adult-onset, eosinophilic asthma phenotype.