The NIH's treatment guidelines for asthma classify asthma by severity, with severe persistent asthma being the most severe type and mild intermittent being the mildest type of asthma.
Now, new research suggests that severe asthma may be an entirely different kind of asthma from the milder forms. The Severe Asthma Research Program (SARP for short) was founded to explore why people with severe asthma tend not to respond as well to treatment.
SARP is a long-term project that has collected data and studied different aspects of asthma. This includes an exploration of the role that genes and viruses might play in the development of asthma.
SARP researchers collected lung function data from 287 patients with severe asthma and 382 people with mild to moderate asthma from 10 different research centers. The data consisted of the following:
- air flow limitation, from narrowed airways
- air trapping from the inability to exhale completely
- reversibility of the airway condition in response to a bronchodilator
- hyperresponsiveness of the airways and immune system
What they found was that though all asthmatics had some degree of airflow limitation, only those with severe asthma also had air trapping. Severe asthmatics also had a less complete reversibility with bronchodilators. Hyperresponsiveness was pretty much the same with all levels of severity, although no participants with the highest levels of severity were included in the study, for fear of setting off an asthma attack.
So, researchers have concluded from these results that severe asthma may be a different form of asthma. 90 to 95% of people with asthma are able to achieve control through medication. But the other 5 to 10% tend to have more asthma attacks and be at higher risk for fatal complications, because they are not able to achieve the same degree of control with medicine.
Now, researchers may be starting to discover clues why. Hopefully, this research will lead to better forms of treatment for severe asthmatics in the future.