“We’re thinking this could be a significant development in the field of chronic cough,” says Peter Hahn, M.D., Mayo Clinic pulmonologist and lead study investigator. The exhaled nitric oxide test measures inflammation in the lungs’ bronchial tubes. The patient breathes into an analyser four or five times over the course of ten minutes. Abnormal scores indicate that the patient has asthma or possibly non-asthmatic eosinophilic bronchitis. This test is much easier for patients and predicts response to corticosteroid treatment better than a commonly used test, the methacholine challenge, according to Hahn.
During the study interval, 114 patients underwent methacholine challenge testing and measurement of exhaled nitric oxide as part of a chronic cough evaluation. Sixty-four of these were either started on inhaled corticosteroids or had their current dose increased to treat chronic cough. Forty-one patients had elevated exhaled nitric oxide levels. Of these, 36 (88 percent) had significant improvement in their chronic cough. Twenty-three patients with exhaled nitric oxide in the normal range also were started on inhaled corticosteroids, and only two had cough improvement.
In contrast, 25 of 39 (64 percent) patients with a positive methacholine challenge test responded to inhaled corticosteroids, but up to 52 percent with a negative methacholine challenge test still had significant improvement of their chronic cough with inhaled corticosteroid therapy. Patients had documented follow-up ranging from four weeks to 12 months.
Study results suggest that measurement of exhaled nitric oxide accurately predicts patients’ response to inhaled corticosteroids for chronic cough, according to the Mayo Clinic researchers.
MEDICA.de; Source: Mayo Clinic