Asthma-COPD Overlap Missed without Adding Bronchodilator Test to Spirometry

There is nearly a 40% chance of overdiagnosing COPD when spirometry is not combined with bronchodilator (BD) testing, often missing asthma and asthma-COPD overlap syndrome (ACOS), according to research at Chest 2019.
COPD and asthma are the most common chronic respiratory disorders in United States. ACOS is a respiratory disorder when you have symptoms of both asthma and COPD. Spirometry with BD testing is recommended but not routinely utilized in clinical practice to diagnose COPD. BD testing will also aid physicians in identifying subjects with possible asthma and ACOS.

To determine the role of bronchodilator testing in avoiding COPD overdiagnosis and to identify subjects with diagnoses such as asthma and ACOS, the researchers evaluated 625 subjects from the National Health and Nutrition Examination Survey (NHANES) data who met American Thoracic Society (ATS) spirometry quality standards and who had airway obstruction based of pre-bronchodilator FEV₁/FVC ratio 1/FVC 1 with BD testing was included in the proposed major criteria and minor criteria of these definitions. Not performing BD testing will limit our ability to identify ACOS subjects using these criteria.

“Not performing BD testing with spirometry and thereby excluding the BDR criteria from definitions might miss 8.6% of ACOS subjects with SEPAR definition and 31% with ATS roundtable definition,” said Annangi.

Asthma is a heterogenous disease and its diagnosis is supported by conundrum of respiratory symptoms typical of asthma (wheeze, shortness of breath, chest tightness or cough) along with the presence of variable expiratory airflow obstruction. The researchers found that among 244 cases (39%) with pre-BD but post-BD ratio 1 > 400 mL and one subject met all three criteria. Respectively, three out of seven subjects, three out of five subjects and three out of seven subjects in the first three aforementioned groups were never told that they had asthma.

“To know whether asthma was suspected and definitively ruled out or was never suspected in those subjects is beyond the scope of our study,” Annangi said. “This is clinically relevant as these subjects with pre-BD ratio