FRIDAY, Jan. 6 (HealthDay News) -- Almost half of patients with mild or moderate asthma may have a different type of disease than those with more severe symptoms, perhaps explaining why common treatments don't work well for them, new research suggests.
"We are beginning to understand that different 'flavors' of asthma probably have different molecular mechanisms," said Dr. John Fahy, director of the Airway Clinical Research Center at the University of California, San Francisco. He is the senior author of the new study, published online Friday in the American Journal of Respiratory and Critical Care Medicine.
Asthma is a chronic disease involving inflamed airways. As the airways become more swollen, the muscles around them can tighten when something triggers symptoms such as coughing, wheezing and shortness of breath.
Current anti-inflammatory treatments target a condition called eosinophilic airway inflammation, which is common in asthma. Eosinophils are a type of white blood cell that help fight off infection and play a role in the immune response.
However, the new research finds that nearly half of the 995 patients studied did not have this condition.
Fahy's team repeatedly measured these white blood cells in sputum samples of the volunteers with asthma who were enrolled in nine clinical trials.
Nearly half, or 47 percent, had no airway eosinophilia on any test of their sputum. Some had the condition intermittently and some had it on each test.
The investigators found that only 36 percent of those not taking an inhaled corticosteroid, an anti-inflammatory, had the condition, while 17 percent of those who used the inhaled steroids did.
After two weeks of giving the participants anti-inflammatories and bronchodilator therapy, Fahy found those with the airway eosinophilia responded and had better airflow. But those who didn't have the co
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