Adult onset asthma: the first 5 years

Adult-onset asthma is a poorly understood, heterogeneous condition. It differs
from childhood-onset asthma in that it is often more severe, less responsive to
therapy and more likely to result in fixed airflow limitation. Several clinical
subtypes of adult onset asthma have been described, but it is unknown whether
these are associated with distinct types of airway inflammation, responses to
therapy or disease outcome. Studies suggest that eosinophilic inflammation that
persists despite corticosteroid treatment is a risk factor of severe disease
and accelerated decline in lung function, especially in the first years of the
disease.

This project is the cross-sectional part of a large-scale longitudinal
follow-up survey in patients with adult-onset asthma. The objective of this
part of the survey is to define different phenotypes of adult onset asthma and
to detect risk factors of severity.

Specific Aims:
1. To define different subtypes of adult-onset asthma, and investigate whether
these subtypes differ with respect to disease severity or quality of life
2. To investigate cross-sectionally whether recent onset asthma differs from
later stages of adult-onset asthma, with respect to clinical, functional and
inflammatory parameters
3. To investigate whether specific subtypes of adult-onset asthma can be
identified by functional or non-invasive inflammatory markers

- Study 1 will represent the baseline part of a longitudinal follow up study of
a cohort of 200 patients with adult-onset asthma. In this study, the patients
will be thoroughly characterized by clinical, functional and inflammatory
markers.

- In study 2, we will cross-sectionally analyse the differences between
patients with recent-onset asthma (1-5 years) and longstanding adult-onset
asthma (> 5 years).

- In study 3, the role of functional and *breatheomics* in the diagnosis of
distinct subtypes of adult-onset asthma will be analysed by cross-sectional
comparison between groups

Study 1 and 2: The burden associated with these studies includes a hospital
visit, during which an intake interview, a physical examination, routine blood
tests ,lung function, exhaled nitric oxide measurement, exhaled volatile
organic compounds analysis (electronic nose) will be done. All subjects will
also perform sputum induction (for differential cell counts and pathogen
detection) which in our own experience as well as based on literature is well
tolerated even by severe asthmatics.

Study 3: Seventy five subjects (who also participated in the previous studies)
will be submitted to nasal endoscopy and sinus CT-scanning for quantitative
scoring of mucosal swelling. The risk of and discomfort caused by these
procedures is small.

The results of the study may be important for the group of asthmatic patients
as it will identify different subtypes of patients with adult-onset asthma and
unravel the underlying mechanisms, which will hopefully lead to
phenotype-specific therapies that might improve outcome in this neglected group
of patients. Thus might also help to reduce the personal and socioeconomic
burden of the disease.