Characteristics and Prevalence of Asthma/Chronic Obstructive Pulmonary Disease Overlap in the United States

Abstract

Rationale: The asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) occurs in patients with fixed airway obstruction that defines COPD and with symptoms more typical of asthma. ACOS prevalence and the comorbidities associated with this syndrome have been inadequately characterized.

Objectives: Because this population is prone to more frequent exacerbations, we hypothesized that comorbidities associated with ACOS are higher than those with COPD, asthma, and control populations in the United States.

Methods: We examined the self-reported demographics, smoking status, comorbidities, and hospitalization or emergency department (ED) visitation experience among study respondents older than 35 years of age (n = 90,851) in the Behavioral Risk Factor Surveillance System survey and compared participants with ACOS to COPD, asthma, and control groups. We used logistic regression to compare ACOS and COPD populations to model the impact of comorbid conditions and hospitalization/ED visits after adjusting for demographic factors and smoking status to generate odds ratios and confidence intervals.

Measurements and main results: The U.S. prevalence of ACOS was 3.2%, COPD alone was 6.0%, and both increased with age. Respondents with ACOS were younger (64.0 ± 11.7 yr) than respondents with COPD (67.1 ± 11.8 yr) and older than respondents with asthma (59.0 ± 13.1 yr; P < 0.0001). The prevalence of comorbidities was higher in the group with ACOS and COPD than in asthma or control groups. The ACOS group had a higher body mass index, lower income, and lower education than other groups. The ACOS group was more likely to have at least one comorbidity (90.2 vs. 84%, P < 0.0001), more hospitalization or ED visits (22.0 vs. 13.2%, P < 0.0001), less exercise (50.0 vs. 58.6%, P = 0.0024), and more disability (70.8 vs. 58.6%, P < 0.0001) than the COPD group.

Conclusions: The patients with a dual diagnosis of asthma and COPD are younger and with more disparities than those diagnosed with COPD alone. ACOS has a higher burden of self-reported comorbidity, disability, and hospitalization or ED visitation than COPD alone.

Keywords: Behavioral Risk Factor Surveillance System; chronic obstructive pulmonary disease; chronic obstructive pulmonary disease–asthma overlap syndrome; comorbidity; hospitalization.