ROLE OF BRONCHODILATOR TESTING IN IDENTIFYING COPD, ASTHMA, AND ASTHMA-COPD OVERLAP SYNDROME: NHANES III ANALYSIS

Abstract

SESSION TITLE: Asthma: From Blood Biomarkers to Biologics and Disease Burden SESSION TYPE: Original Investigations PRESENTED ON: 10/21/2019 1:30 PM - 2:30 PM PURPOSE: Spirometry with Bronchodilator (BD) testing is not routinely utilized in clinical practice to diagnose chronic obstructive pulmonary disease (COPD) despite the recommendation to use the post BD ratio of forced expiratory volume in the first second (FEV1) over forced vital capacity (FVC).1,2 We aimed to determine the role of BD testing in avoiding COPD overdiagnosis and identifying subjects with possible alternate diagnosis like asthma and asthma-COPD overlap syndrome (ACOS). METHODS: The National Health and Nutrition Examination Survey (NHANES) data was analyzed from 2007-2012.3 Subjects age ≥ 40 years with spirometry studies meeting the American Thoracic Society (ATS) quality standards were included. Blood eosinophil count ≥ 300cells/μL and FEV1 change > 12% and > 200ml with BD testing were used to define blood eosinophilia and BD reversibility (BDR) respectively. Asthma history was identified using NHANES question “Has a doctor or health care professional ever told that you have Asthma?”. Subjects with probable ACOS were identified using two major criteria (Post-BD FEV1/FVC < 0.7, and asthma history or FEV1 change ≥ 400ml in cases without asthma history) along with any one minor criteria (BDR or blood eosinophilia).4 Post-BD FEV1/FVC ≥ 0.7 with BDR and/or blood eosinophilia were used to identify probable asthma cases. We analyzed non-weighted samples using SPSS version 21. RESULTS: We identified 8002 subjects age ≥40 years who completed pre-BD spirometry testing, 625 of them met ATS spirometry quality standards and had a pre-BD FEV1/FVC < 0.7. Of these 625 subjects, 381(61%) had post-BD FEV1/FVC < 0.70 confirming irreversible airway obstruction. Among these 381 subjects with post-BD FEV1/FVC < 0.7, twelve (3.1%) subjects had asthma history and BDR; 16 (4.2%) had asthma history and blood eosinophilia; 2 (0.7%) had FEV1 change ≥ 400ml and blood eosinophilia making ACOS more likely than COPD alone in these subjects. Among the remaining 244 cases (39%) with pre-BD FEV1/FVC < 0.7 but post- BD ratio ≥ 0.7, twenty-four (9.8%) had BDR alone and 10 of these had BDR and eosinophilia making asthma more likely. Moreover, 18 of the 24 subjects with BDR and 6 of the 10 subjects with BDR and eosinophilia had no prior asthma history and would likely be misdiagnosed as COPD if pre-BD FEV1/FVC ratio alone was used. CONCLUSIONS: Routine underutilization of spirometry with BD testing may lead to over diagnose 39% of subjects as having COPD. Further evaluation for potential asthma would be needed in 9.8% of these subjects. Moreover, post-BD spirometry values along with the recommended criteria for ACOS help identify 8% of COPD subjects who likely have ACOS. CLINICAL IMPLICATIONS: Routine use of Post-BD spirometry values will not only prevent over diagnosis of COPD but also help identifying subjects with potential ACOS and asthma. DISCLOSURES: No relevant relationships by Srinadh Annangi, source=Web Response No relevant relationships by Angel Coz Yataco, source=Web Response