The multiple dimensions of airways disease: targeting treatment to clinical phenotypes

The recognition that asthma and chronic obstructive pulmonary disease (COPD) are not single diseases, but syndromes made up of multiple separate disorders that overlap, has led to attempts to develop a new taxonomy for the disorders of airflow obstruction. A better understanding of the distinct disorders of airways disease has the potential to inform on underlying mechanisms, risk factors, natural history, monitoring and treatment.

Recent attempts to describe the different phenotypes have largely been based on cluster analysis. Preliminary evidence suggests that there may be five distinct phenotypes of airways disease. To date, however, no simple allocation criteria have been validated that enable clinicians to allocate individual patients to specific phenotypic groups. The concept of differential treatment responses in different phenotypes of airways disease has been established with the demonstration that eosinophilic asthma preferentially responds to inhaled corticosteroid therapy or monoclonal antibody against interleukin-5, and severe refractory noneosinophilic asthma to macrolide antibiotics.

The priority is to further define the distinct phenotypes that make up the syndromes of asthma and COPD. This knowledge could lead to treatments specifically targeted for defined phenotypic groups, rather than for asthma and COPD in general, which represents the current management approach.