Emergency department (ED) visits for Asthma and Chronic Obstructive Pulmonary Disease (COPD) are common. The designation of Asthma-COPD overlap (ACO) has been used to describe patients with features of both diseases. Studies show that ACO patients may be at increased risk of poor outcomes relative to patients with either disease alone. We sought to characterize ED visits and ED-related outcomes of patients with ACO compared to patients with Asthma or COPD alone.

We conducted a secondary analysis of the National Hospital Ambulatory Medical Care Survey (NHAMCS, 2005–2018) characterizing ED visits in patients ≥35 years of age with Asthma Only, COPD Only or ACO. We performed univariable and multivariable analyses adjusting for demographics to assess relevant ED outcome variables.

From 2005 to 2018, there were an estimated 8.15, 17.78 and 0.56 million ED visits for Asthma Only, COPD Only and ACO, respectively. ACO patients were younger than COPD Only patients (mean age 50.18 versus 61.79; p < 0.001). ACO patients differed in terms of sex, race and ethnicity from patients with either disease alone. When triaged, Asthma Only (adjusted odds ratio (aOR) = 11.45; 95% confidence interval (CI), 1.20–109.38) patients were more likely to require immediate care than ACO patients. Although admission rates were comparable between groups, ACO patients had a decreased mean length of ED visit compared to both Asthma Only (p < 0.001) and COPD Only (p < 0.05) patients. COPD Only patients were less likely than ACO patients to be seen in the ED in the last 72 h (aOR = 0.22; 95% CI, 0.056–0.89), receive nebulizer therapy (aOR = 0.55; 95% CI, 0.31–0.97), bronchodilators (aOR = 0.24; 95% CI, 0.12–0.48) and systemic corticosteroids (aOR = 0.18; 95% CI, 0.091–0.35). Asthma Only patients were less likely than ACO patients to undergo any imaging (aOR = 0.55; 95% CI, 0.31–0.96) and receive antibiotics (aOR = 0.46; 95% CI, 0.23–0.93).

ACO patients appear to differ demographically from patients with either disease alone in the ED. After adjustment for these demographic differences, ACO patients appear to differ with respect to several ED variables, notably respiratory therapies; however, clinical outcomes including admission and mortality rates appear to be comparable between groups.