Researchers report there are important differences between people with severe and non-severe asthma, something that could help explain why those with severe asthma don’t respond well to treatment.

The study, from the Severe Asthma Research Program (SARP), looked at 287 people with severe asthma and 382 people with mild or moderate asthma. It found that people with severe asthma are more likely to show signs of “air trapping” in the lungs, a condition that prevents full exhalation. In addition, those with severe asthma are more likely to have airway obstruction even after maximal treatment. These findings suggest that severe asthma may be a different form of the disease, the researchers said.

“This tells us that something entirely different is going on in people classified as having severe asthma, either physiologically or in the airways that are affected,” study author Ronald Sorkness, a physiologist at the University of Wisconsin in Madison, said in a prepared statement.

The findings were published online in the Journal of Applied Physiology.

About 90 percent to 95 percent of asthma cases can be controlled with medication, but 5 percent to 10 percent of people have a severe form of asthma that doesn’t respond well to treatment. People with severe asthma are likely to have more attacks and are at increased risk for a fatal attack. Each year, asthma causes about 4,200 deaths in the United States.

SARP was formed to learn more about severe asthma and improve treatment of the condition.

(Source: NHIC)