Is spirometry essential in diagnosing asthma? No

Post date: Aug 27, 2016 8:51:14 AM

Asthma is a chronic respiratory disease characterised by fluctuating respiratory symptoms and reversible airflow obstruction. Confirmation of the diagnosis hinges on demonstrating airflow obstruction varying over time. Patients with undiagnosed asthma who consult repeatedly with symptoms ranging in severity may demonstrate perfectly normal spirometry.

As there is no single ‘gold standard’ test, clinical asthma diagnosis is based on evidence of recurrent respiratory symptoms; reversibility with anti-asthma treatment; and variable airflow obstruction. Demonstrating any, or all three, of these features in a clinical setting is challenging: the disease fluctuates. The diagnosis is clear cut if spirometry in a patient with a history suggestive of asthma demonstrates airflow obstruction with reversibility. However, if the test is normal, asthma cannot be excluded.

Is spirometry the most practical test? It would be, if patients could guarantee to exhibit airflow obstruction at the time spirometry is performed; clearly they cannot, and this practical and logistic issue limits the feasibility and usefulness of this investigation in every case.

by Mark L Levy

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