Comparison of Health Characteristics in Subjects With Asthma, COPD, and Asthma-COPD Overlap Using the NHANES Database

Abstract

SESSION TITLE: New Perspectives in COPD Morbidity SESSION TYPE: Original Investigation Slide PRESENTED ON: Sunday, October 29, 2017 at 07:30 AM - 08:30 AM PURPOSE: It is increasingly recognized that both asthma and chronic obstructive pulmonary disease (COPD) are heterogeneous diseases with a large inter-individual variability with respect to their clinical expression. We examine whether subjects in a national survey, reporting both asthma and COPD, share characteristics commonly associated with asthma severity (i.e. blood eosinophil counts (EOS) ≥150 cells/μL, asthma attacks, emergency room visits for attacks) or if they are more likely to share attributes of COPD (i.e. decreased lung function, clinical markers of bronchitis such as phlegm, comorbidities). METHODS: This US population-based cross-sectional study used the National Health and Nutrition Examination Survey (NHANES) data (2009-2012) to define three mutually exclusive disease states: asthma, COPD and asthma-COPD overlap. Groups were compared using Chi-squared tests for categorical variables and Student t-tests for continuous measures. RESULTS: A total of 1,609 subjects with asthma, 479 with COPD, and 299 with asthma-COPD overlap were identified. Among demographic factors, mean (±SD) age was lower for asthma (36.8±0.6, p<.001) but similar for the COPD and overlap groups (60.6±0.4 vs 60.0±0.7, p=0.444). Approximately 9.5% of the overlap group described their general health status as poor compared with less than 3% of the other groups. The overlap group also averaged 8 days of poor health and 5 days of inactivity due to poor physical/mental health within the last 30 days, compared to 5 days or less for physical health and 2 days of inactivity for the asthma and COPD groups. Compared with the asthma group, the overlap group was not different in mean (±SD) EOS counts (232.7±6.9 vs 247.6±13.6 cells/μL, p=0.291), but did have a larger percent of subjects with EOS ≥400 cells/μL (16.9% vs 11.6%, p=0.041). Approximately half of both groups had asthma attacks in the prior year and there was no statistically significant difference in the number of emergency visits (21.9% vs 14.8%, p=0.148). Compared with the COPD group, the overlap group had lower pre-bronchodilator FEV1 and FVC, but the post-bronchodilator lung function test was similar. There were no differences in average BMI or rates of hypertension between these groups, yet the overlap group did have a significantly higher percent of subjects compared to the COPD group with coronary heart disease (25.6% vs 13.9%, p=0.003), stroke (9.2% vs 4.5%, p=0.002) and diabetes (26.0% vs 15.9%, p=0.014). The percent of the overlap group who experienced phlegm most days in the past three months was higher compared with the COPD group (25.7% vs 19.6%, p<.001). CONCLUSIONS: The results of this study indicate that subjects with asthma-COPD overlap share some clinical characteristics with subjects with asthma or COPD only; yet they have other characteristics indicating increased burden of disease over the individual diseases. CLINICAL IMPLICATIONS: These results suggest that the asthma-COPD overlap group represents a distinct population. DISCLOSURE: Beth Hahn: Employee: Stock Christopher Bell: Employee: stock Jean-Pierre Llanos: Employee: stock Hector Ortega: Employee: stock The following authors have nothing to disclose: Marie-Helene Lafeuille, Mei Sheng Duh, Guillaume Germain, Sean Tiggelaar No Product/Research Disclosure Information