Researchers from the Mayo Clinic found an asthma diagnostic test - the exhaled nitric oxide test - as an inexpensive and easy way to determine whether inhaled corticosteroids will relieve a patient's chronic cough.

According to Peter Hahn, M.D., Mayo Clinic pulmonologist and lead study investigator:

"We're thinking this could be a significant development in the field of chronic cough. 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. It helps us get to the treatment and bring relief to the patient in the least invasive, fastest way possible."

Cough is the third most common reason for a patient to visit a physician while chronic cough is variably defined as three to eight weeks of prolonged cough. Upper airway cough syndrome (also known as postnasal Drip syndrome), asthma, and gastroesophageal reflux are the three major diagnoses that cause chronic cough.

Of course, patients will see a physician because chronic coughing disrupts their lives, particularly daily activities. In fewer cases, chronic cough is due to non-asthmatic eosinophilic bronchitis.

In the exhaled nitric oxide test, the patient breathes into an analyzer four or five times over the course of 10 minutes in order to measure the inflammation in the lungs' bronchial tubes.

Dr. Hahn added:

"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.

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."

The details of this study have been presented in an abstract at the European Respiratory Society Meeting in Munich, Germany on September 6.

Read more at EurekAlert.