Asthma is over-diagnosed in approximately 30% of adult North Americans; that is the abbreviated conclusion of a new Canadian study presented at the recent ATS 2016 International Conference. Lack of spirometry testing among physicians may be the primary culprit.
Step 1 in determining a diagnosis of asthma is to first determine that airway obstruction is present. As the latest NAEPP Asthma Guidelines state “In all patients age ≥5 years of age, use spirometry to determine that airway obstruction is at least partially reversible.” The guidelines also recommend that asthma patients be monitored with spirometry testing at least every 1-2 years.
However, of those asthmatic patients in the study only 49% received a spirometry test at the time of their diagnosis. Not surprisingly, of 613 patients with a physician diagnosis of asthma, appropriate testing later revealed that 230 or 37.5% of these patients did not currently have asthma!
Diagnosing asthma without spirometry increases the chance of misdiagnosis and associated issues arising from missed alternative diagnoses or unnecessary use of asthma medications.