Investigators using the National Health and Nutritional Examination Survey (NHANES) pinpointed the clinical characteristics of asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) as a unique patient group with greater disease burden and poorer quality of life, as compared with patients with COPD or asthma.
Asthma-COPD overlap (ACO) is a disease with characteristics of both asthma and COPD. Even with increasing knowledge of both asthma and COPD, there are not many treatment guidelines for ACO, possibly because of the lack of understanding of the characterizations of ACO.
NHANES is a yearly representation of self-reported illnesses and health status that provides a dataset for ACO as well as asthma and COPD. By using data from the NHANES, investigators sought to describe the clinical characteristics and health status of ACO to help clinicians separate ACO from either asthma or COPD.
Patients in the NHANES dataset were classified into 3 groups: asthma, COPD, and ACO. Patients were categorized into the asthma group if they reported ever being diagnosed with asthma or having an asthma attack within the past 12 months.
Patients were categorized into the COPD group if they were at least 40 years old, had a forced expiratory volume in 1 second (FEV1
)/forced vital capacity (FVC) < .70 even after using their β2-brochodilator medication, or if they had emphysema or chronic bronchitis.
Patients in the ACO group had to be at least 40 years old and meet at least 1 characteristic from both the asthma and COPD group. To exclude age as a characterization factor, patients in the asthma group were subcategorized so that the age of the asthma group matched the ACO and COPD group.
In terms of general health, a greater proportion of patients with ACO said that their health was poor, compared with patients from either the COPD or asthma group. Patients with ACO also reported poorer physical health and more inactivity due to physical and mental health compared with the other 2 groups. Additionally, productivity and daily work were significantly lower in the ACO group. When examining health care and hospital visits, investigators found that patients with ACO received more care than either patients with COPD or asthma.
In addition, investigators found that the prevalence of other comorbid conditions (diabetes, kidney disease, stroke, coronary artery disease, hypertension) were higher in the ACO group compared with the other 2 groups. Patients classified into the ACO group also smoked significantly more cigarettes than the asthma group, and more, although not significant so, than the COPD group.
Airway obstruction, measured by the prebronchodilator percentage of predicted FEV1
was lower in the ACO group than the asthma group but comparable to the COPD group. Mean eosinophil counts were relatively similar between the asthma and ACO group, but significantly higher for these 2 groups compared with COPD group and the asthma group.
In general, patients with ACO had greater disease severity, more healthcare visits, and a greater number of comorbidities compared with patients with COPD or asthma. By effectively classifying ACO in its own disease category distinct from both asthma and COPD, early identification may initiate earlier treatment and more inclusion into clinical trials.
Llanos JP, Ortega H, Germain G, et al. Health characteristics of patients with asthma, COPD and asthma-COPD overlap in the NHANES database. Int J Chron Obstruct Pulmon Dis.
2018;13:2859-2868. doi: 10.2147/COPD.S167379.