Cough lasting for a few weeks or longer is termed chronic cough. Postnasal drip syndrome, asthma and gastroesophageal reflux are the major causes of this condition. Chronic cough may be sometimes caused by non-asthmatic eosinophilic bronchitis.
The exhaled nitric oxide test; a test commonly used for asthmatics, is a great deal simpler for patients and predicts response to corticosteroid treatment better than the other commonly used test; the methacholine challenge. This was the conclusion arrived at by the study conducted on 114 patients to assess chronic cough.
"We're thinking this could be a significant development in the field of chronic cough," study lead investigator and Mayo Clinic pulmonologist Dr. Peter Hahn said in a prepared statement.
"It could drastically change what we do for patients with chronic cough and also the guidelines for diagnosis and treatment of chronic cough. This very accurate -- but rather underused -- test could be used up front for all patients complaining of chronic cough, saving significant time and expense in other testing," he said. "It helps us get to the treatment and bring relief to the patient in the least invasive, fastest way possible."
Inflammation in the bronchial tubes of the lungs is measured by the exhaled nitric oxide test. In this test, the patient is made to breathe into the analyzer four or five times over 10 minutes. Asthma or probably non-asthmatic eosinophilic bronchitis is indicated by the abnormal scores.
In these conditions, inflammation irritates the airway and triggers coughing in the patients. Inflammation can be reduced by corticosteroids and hence, cure this type of chronic cough.
"Patients with a positive, or abnormal, exhaled nitric oxide test had a strong likelihood of response to inhaled corticosteroids, whereas a negative, or normal, exhaled nitric oxide test virtually excluded response to the medication," Hahn said. Use of the test "may potentially have a significant impact on how patients with chronic cough are evaluated and treated," he said.
The findings were presented on Sept. 6 at the European Respiratory Society Meeting in Munich, Germany.