Asthma Test for Chronic Cough
Test Could Help Doctors Better Treat Chronic Cough
WebMD News Archive
Sept. 6, 2006 -- An asthma test may change the way doctors evaluate and
treat chronic cough.
Researchers at the Mayo Clinic today reported that a test called the exhaled
nitric oxide test, commonly used for asthma patients, can help predict which
chronic cough patients would be helped by inhaled corticosteroids.
In the exhaled nitric oxide test, the patient breathes into a device four or
five times over 10 minutes. The device then measures nitric oxide in the
patient's exhaled air.
The test isn't new. Currently, it is used to look for inflammation of the
airways, a symptom of asthma.
But the test may also help evaluate and guide treatment of chronic cough,
which is a cough that lasts more than eight weeks, note Peter Hahn, MD, and
colleagues at the Mayo Clinic in Rochester, Minn.
Hahn's team presented promising results for the exhaled nitric oxide test
today at the 16th European Respiratory Society Congress, held in Munich,
'Drastic Change' Ahead?
"We're thinking this could be a significant development in the field of
chronic cough," Hahn says, in a Mayo Clinic news release.
"It could drastically change what we do for patients with chronic cough
and also the guidelines for diagnosis and treatment of chronic cough," he
Chronic cough is usually due to asthma, postnasal drip, or gastroesophageal
reflux (GERD), the
researchers note. A less common cause is eosinophilic bronchitis.
Asthma and eosinophilic bronchitis can be treated with inhaled
corticosteroids, which combat inflammation in the airways to reduce asthma
In their study, Hahn's team reviewed the medical charts of 114 chronic cough
patients seen at the Mayo Clinic.
The patients had taken the exhaled nitric oxide test. They had also
performed methacholine challenge testing, in which patients inhale a chemical
called methacholine as part of a lung function test.
Of those two tests, the exhaled nitric oxide test was better at predicting
which chronic cough patients would be helped by inhaled corticosteroids, the
A total of 47 patients had high levels of exhaled nitric oxide. Of those
patients, 41 started using inhaled corticosteroids, and 36 noted improvement in