Identification of COPD, asthma and overlap syndrome can be teased out with spirometry following use of bronchodilator

NEW ORLEANS, Oct. 14, 2019 /PRNewswire/ -- There is nearly a 40% chance of overdiagnosing chronic obstructive pulmonary disease (COPD) when spirometry is not combined with bronchodilator (BD) testing, often missing asthma and asthma-COPD overlap syndrome (ACOS), according to Srinadh Annangi, MD, from the University of Kentucky, School of Medicine, who will present the study findings at the CHEST Annual Meeting 2019 in New Orleans.

COPD and asthma are the most common chronic respiratory disorders in United States. ACOS is a respiratory disorder when you have symptoms of both asthma and COPD. Spirometry with BD testing is recommended but not routinely utilized in clinical practice to diagnose COPD. BD testing will also aid physicians in identifying subjects with possible asthma and ACOS.

To determine the role of bronchodilator testing in avoiding COPD overdiagnosis and to identify subjects with diagnoses such as asthma and ACOS, the researchers evaluated 625 subjects from the National Health and Nutrition Examination Survey (NHANES) data who met American Thoracic Society (ATS) spirometry quality standards and who had airway obstruction based of pre-bronchodilator FEV₁/FVC ratio <0.7.

Of the study subjects, 625 who showed evidence of pre-BD FEV₁/FVC ratio <0.7 can potentially be mislabeled as COPD if BD testing was not performed. However, only 381 or 61% of these continued to present an airway obstruction after BD testing (post-BD FEV₁/FVC <0.7), thereby confirming the diagnosis of COPD. "Not performing BD testing routinely and relying on pre-BD FEV₁/FVC ratio will lead to COPD overdiagnosis in 40% of subjects," explained Dr. Annangi.

ACOS subjects with features of both COPD and asthma can be identified using modified Spanish Society of Pneumology and Thoracic Surgery (SEPAR) or ATS roundtable criteria. Differentiating COPD from overlap syndrome is of clinical importance, owing to differences in clinical management and outcomes. Prevalence of possible ACOS among the COPD subjects was 19.0% (70 out of 368) when modified Spanish definition was applied and 7.9% with modified ATS definition. Change in FEV₁ with BD testing was included in the proposed major criteria and minor criteria of these definitions. Not performing BD testing will limit our ability to identify ACOS subjects using these criteria.

"Not performing BD testing with spirometry and thereby excluding the BDR criteria from definitions might miss 8.6% of ACOS subjects with SEPAR definition and 31% with ATS roundtable definition," explained Dr. Annangi.

Asthma is a heterogenous disease and its diagnosis is supported by conundrum of respiratory symptoms typical of asthma (wheeze, shortness of breath, chest tightness or cough) along with the presence of variable expiratory airflow obstruction. The researchers found that among 244 cases (39%) with pre-BD but post-BD ratio <0.7, 24 subjects (9.8%) had positive BDR. Among 24 of these subjects with positive BDR, seven experienced wheezing in the past year, five had family history of asthma, seven had change in FEV₁ > 400 mL and one subject met all three criteria. Respectively, three out of seven subjects, three out of five subjects and three out of seven subjects in the first three aforementioned groups were never told that they had asthma.

"To know whether asthma was suspected and definitively ruled out or was never suspected in those subjects is beyond the scope of our study," Dr. Annangi commented. "This is clinically relevant as these subjects with pre-BD ratio <0.7 would have otherwise be diagnosed as COPD if BD testing was not performed when they potentially need to be evaluated for asthma diagnosis."

The researchers wrote: "Routine underutilization of spirometry with BD testing may lead to overdiagnose 39% of subjects as having COPD. Further evaluation for potential asthma would be needed in 3.8% of these subjects. Prevalence of ACOS was estimated at 7.9% to 19% based on definition used. Not performing BD testing and excluding the BDR criteria will miss a significant proportion (8.6% to 31%) of possible ACOS subjects. When identifying ACOS subjects, ATS definition relies more on post-BD spirometry values compared with SEPAR definition."

"Routine use of post-bronchodilator spirometry values will not only prevent overdiagnosis of COPD but also help identifying subjects with potential ACOS and asthma," they concluded.

Victor Test, MD, Co-Chair of the CHEST Scientific Program Committee and Professor of Texas Tech University Health Sciences Center, commented: "This well-designed study clearly demonstrates the importance of spirometry with the use of bronchodilators to identify COPD as well as asthma and overlap syndromes. It once again emphasizes the importance of pulmonary physiological testing when obstructive lung disease is a possibility."

MEETING
Further results from this study will be shared at CHEST Annual Meeting 2019 in New Orleans on Monday, Oct. 21, 2:15 p.m. to 2:30 p.m., at the Ernest N. Morial Convention Center, Room 267. The study abstracts can be viewed on the journal CHEST® website.

ABOUT CHEST 2019
CHEST 2019 is the 85th annual meeting for the American College of Chest Physicians held Oct. 19 to Oct. 23, 2019, in New Orleans. The American College of Chest Physicians, publisher of the journal CHEST®, is the global leader in advancing best patient outcomes through innovative chest medicine education, clinical research and team-based care. Its mission is to champion the prevention, diagnosis and treatment of chest diseases through education, communication and research. It serves as an essential connection to clinical knowledge and resources for its 19,000 members from around the world who provide patient care in pulmonary, critical care and sleep medicine. For more information about CHEST 2019, visit chestmeeting.chestnet.org, or follow CHEST meeting hashtag, #CHEST2019, on social media.

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SOURCE American College of Chest Physicians

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