Validatity of Nitric Oxide Test for Asthma Questioned
The discriminate ability of the fraction of exhaled nitric oxide (FENO) test as an evaluation tool for asthmatic patients was questioned in a recent article published in the American Journal of Respiratory and Critical Care Medicine.
FENO has been identified as a potential marker of inflammation in the airway. The research team from New Zealand set to determine reference ranges for this testing approach, in order to improve diagnostic utility the test. They also sought to determine factors associated with FENO findings.
Patients between ages 25 and 75, a total of 3,500, were recruited to participate in a study to assess respiratory status. Notably, the recruited samples was comprised almost entirely of white subjects, given the population of the study area in Wellington, New Zealand. Nevertheless, this was a random sample of residents.
795 patients from the original sampling completed questionnaires detailing relevant medical history, as well as undergoing FENO and pulmonary function testing. FENO evaluation was completed using an online nitric oxide monitor.
The geometric mean of FENO values in the normal healthy participants was 17.9 parts/billion with a 90 percent confidence interval. Smoking status, atopy, and gender all moderated FENO levels. Men had higher levels than women, as did atopic individuals and smokers. On the basis of these findings, the group calculated adjustments in the reference ranges for these subsets.
Patients with either allergic rhinitis and asthma has higher FENO scores as well. However, findings indicated that the test did not demonstrate sufficient sensitivity to justify use as a screening tool.
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August 17, 2007 Related topics: Pulmonary, Diagnostic, Allergy & Immunology