“Most asthmatics get symptomatic relief from their disease,” Dr. Happel observed.
And, if there is no indication in the patient’s chart that the asthma diagnosis was based upon demonstration of airflow obstruction on spirometry, the diagnosis is thrown further into doubt. In the recent Canadian study, patients who didn’t undergo pulmonary function testing (PFT) to establish airflow limitation at their time of diagnosis were significantly less likely to have current asthma.
“I would strongly suggest everyone with the diagnosis of asthma get spirometry with bronchodilator testing,” Dr. Happel said. “Good-quality PFTs are critical in forming a solid diagnosis of asthma.”
In a patient who has symptoms consistent with asthma, a 200-cc and 12% or more improvement in forced expiratory volume in 1 second (FEV1) in response to bronchodilator challenge is supportive of the diagnosis. However, absence of reversible airway obstruction doesn’t exclude the possibility of asthma.