Asthma-COPD Overlap Syndrome- an Underdiagnosed Phenotype in Heavy Smokers

Rationale: Asthma-Chronic Obstructive Pulmonary Disease (COPD) Overlap Syndrome (ACOS) is an obstructive airway disease with features of both asthma and COPD, and its identification has significant therapeutic implications.  While ACOS has been studied in patients with low smoking history, its characteristics have not been examined in heavy smokers. 

Methods: To examine the characteristics of ACOS in heavy smokers, we performed a cross-sectional study in veterans who underwent pulmonary function testing in 2013 and 2014 at the San Francisco Veterans Affairs (VA) Medical Center.  All patients who met the Global Initiative on Obstructive Lung Disease (GOLD) criteria for COPD were included in the study.  The VA electronic health records were queried for demographics and presence of asthma.  Statistical analysis performed with STATA.

Results: Of the 261 patients with COPD who have been reviewed so far (67+/-5 years old, 97% men, 46+/-5 pack-years of smoking), 68 (26.05%) had ≥12% and ≥200 ml reversibility in FEV1 post-bronchodilator, and thus met the criteria for diagnosis of ACOS.  Among those, 20 (7.7% of total) had highly positive bronchodilator test (≥15% and ≥400 ml reversibility in FEV1 post-bronchodilator).  Nineteen of 68 patients with ACOS (27.9%) and 7 of 20 patients with highly positive bronchodilator test (35%) had documented diagnosis of asthma.

Conclusions: ACOS is an under-recognized but common diagnosis in veterans with heavy smoking and COPD.  Given the therapeutic and prognostic implications of ACOS illustrated in previous studies, all patients with COPD, even those with history of heavy smoking, should be evaluated for ACOS.