Breath Test Determines Treatment for Chronic Cough

A simple, inexpensive breath test determines whether inhaled corticosteroids will relieve a patient's chronic cough.

The exhaled nitric oxide test measures inflammation in the lungs' bronchial tubes. The patient breathes into an analyzer four or five times over the course of 10 minutes. Abnormal scores indicate that the patient has asthma or possibly non-asthmatic eosinophilic bronchitis. Both conditions can be effectively treated with inhaled corticosteroids. In these patients, inflammation irritates the airway and prompts coughing. Corticosteroids help reduce the inflammation, alleviating the cough.

This test is much easier for patients and predicts response to corticosteroid treatment better than the commonly used test, the methacholine challenge, according to Peter Hahn, M.D., a pulmonologist at the Mayo Clinic (Rochester, MN, USA). A study was conducted via chart review of consecutive patients evaluated at Mayo Clinic for chronic cough using both exhaled nitric oxide and methacholine challenge testing between December 2004 and November 2005. Results were presented in an abstract presented at the European Respiratory Society Meeting in Munich (Germany) in September 2006.

"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,” said Dr. Hahn. "The accuracy of the exhaled nitric oxide test in predicting response to inhaled corticosteroids for chronic cough appears to be better than with methacholine-challenge testing. This may potentially have a significant impact on how patients with chronic cough are evaluated and treated.”

Dr Hahn said that the next step needed in testing for chronic cough is a prospective study comparing the utility of the methacholine challenge versus the exhaled nitric oxide test.



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