Getting the Diagnosis Right
Medscape: In the new guidelines, you make a very clear, strong point that the diagnosis of EIB requires lung function testing provoked by exercise, and it should not be made on the basis of clinical symptoms. What is commonly happening in clinical practice?
Dr. Parsons: We have done a study, and data from multiple other studies show that the vast majority of clinicians, whether primary care doctors or specialists, are diagnosing EIB on the basis of symptoms alone. In some of our previous work, we have shown that in up to 70% of cases when a patient comes in with symptoms during exercise, they are attributed to EIB without any kind of form of diagnostic testing.
Now the problem with that is, as I just mentioned, many of the symptoms that can happen during exercise -- shortness of breath, chest tightness -- have nothing to do with asthma. So when we treat on the basis of symptoms alone, it's like tossing a coin in terms of whether or the patient is being treated for the proper diagnosis. So we really encourage clinicians, if they feel that the diagnosis of EIB is potentially present, to do an appropriate test to document it formally.
Medscape: What is the test, and where are patients sent to have it done?
Dr. Parsons: The tests are serial lung function measurements after specific exercise or a hypernea challenge. Most primary care clinicians will have access to, at least at their local hospital, a pulmonary function laboratory where they can refer their patients for formal testing. Very few people are going to have access to testing in their offices, so it would require them to order the test and have the patient go to their local hospital to have it done in the pulmonary function laboratory.
Medscape: According to the guideline, the testing grades the severity of EIB depending on the percent fall in FEV1 compared with the pre-exercise level. How is this information used?
Dr. Parsons: Patients with bronchospasm tend to be poor receivers of how severely they are impaired. They are often not able to connect with how much they are dropping. It's hard for them to tease out the symptoms of intense exercise from the symptoms of bronchoconstriction.
This is another reason why it is so important to do the testing rather than just rely on symptoms, because many times, these patients won't make the connection that something is wrong here. It's for patient education; it gives the patient some idea of how severe their bronchospasm is if you can say, "Look, you dropped 30%." It may also be necessary to show them the severity of their EIB to convince some patients that they need treatment before they exercise.
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Cite this: Exercise-Induced Bronchoconstriction: The New Guidelines - Medscape - Feb 03, 2014.