To the Editors:
The study of Luks et al. 1 highlights an area of asthma care that has important patient and economic implications. The authors strive to answer a very relevant clinical question related to practical clinical considerations surrounding asthma diagnosis: how many steps of a diagnostic algorithm are required to confirm diagnosis of asthma among patients previously diagnosed with asthma in the community? The authors demonstrate that >90% of patients were confirmed with only one or two study visits by either pre- and post-bronchodilator spirometry or a single bronchial challenge test. Based on the protocol design, the patients studied at visit 1 and visit 2 were similar, since steroid tapering did not occur until visit 3. From figure 1 in 1, it appears that 54 out of 499 (10.8%) patients were diagnosed with asthma using simple pre- and post-bronchodilator spirometry. At visit 2, methacholine challenge testing resulted in a confirmation rate of 274 out of 444 (61.7%) patients and an exclusion rate of 121 out of 444 (27.3%) patients. In order to identify the most simple and practical approach to asthma diagnosis confirmation in this population, a methacholine challenge test (MCT) should have been performed at visit 1. It is possible that some, if not most, of the spirometrically confirmed cases (visit 1) would also be confirmed with MCT. This issue is relevant because it would provide practical information about which test should be ordered first in the real world; the results of the study by Luks et al. 1 suggest that MCT may be the option of choice among this population. If primary care physicians are to be encouraged to adopt a role in confirmation of asthma diagnosis in the community, this issue requires further clarification. The design of the current algorithm may actually underestimate its utility in terms of the number of visits required to confirm asthma diagnosis; this may turn out to be a one-visit process for most patients.
Given the algorithm design, it would be more clear to state that at least two visits were required to confirm or exclude a diagnosis of asthma in the majority of patients. Further studies are needed to determine how simple spirometry compares to MCT for de novo asthma diagnosis in the community setting.
Footnotes
Statement of Interest
Astatement of interest forA.D'Urzo can be found at www.erj.ersjournals.com/site/misc/statements.xhtml
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