Researchers have identified key characteristics of severe asthma that can help in developing new treatments for patients with the condition.
The findings come from one of the largest assessments of adults with severe asthma to date, looking at several characteristics including symptoms, patients' quality of life and blood and airway measurements.
The U-BIOPRED (Unbiased BIOmarkers in PREDiction of respiratory disease outcomes) project was established in 2008 to better understand severe asthma and identify new treatment targets.
The European study involved four groups of adult participants in 11 countries and followed them up for over a year; 311 non-smokers with severe asthma, 110 smokers and ex-smokers with severe asthma, 88 patients with milder asthma and 101 healthy volunteers.
As part of the study, blood, urine and sputum (mucus) samples were collected and lung function and other anatomical tests were performed.
The results found that patients with severe asthma had more symptoms and exacerbations compared to patients with mild-moderate disease.
Severe asthma patients also reported worse quality of life and higher levels of anxiety and depression as well as more nasal polyps (small growths in the nose), acid indigestion and poorer lung function.
A key finding was that although patients with severe asthma take greater amounts of anti-inflammatory treatment, including inhaled and oral steroids, they still had higher levels of inflammation in their airways.
"This study is the first to describe severe asthma across such a large cohort. Our findings are consistent with other recent descriptions of the condition and will enable us now to identify distinct asthma phenotypes, or subgroups," said lead author of the paper Dr Dominick Shaw, from the University of Nottingham in the UK.
"Once we can break this condition down into different groups, patients can be swiftly and accurately diagnosed and individually treated by targeting the mechanisms that are driving their own disease.
"Once we can identify these new treatments, we can lessen the burden of this chronic and debilitating disease," Shaw said.
The study was published in the European Respiratory Journal.
