COPD-Asthma overlap

Exhaled nitric oxide testing is a valuable tool for diagnosing asthma due to its good positive predictive value for isinophilic inflammation. Physicians may not be ordering this test frequently enough, especially in the context of the increasing prevalence of COPD asthma overlap. The test can also assist in diagnosing non-asthmatic isinophilic bronchitis and determining COPD asthma overlap, although its negative predictive value is limited. Factors like smoking and using inhaled corticosteroids can impact the accuracy of the test results, making it more useful when the results are positive.