Asthma and Chronic Obstructive Pulmonary Disease Overlap: The Effect of Definitions on Measures of Burden

Abstract

Background: Although the overlap between asthma and COPD has been recognized for years this overlap has only recently been given a name, asthma-COPD overlap syndrome (ACOS), and better defined. Different definitions of the component diseases can affect prevalence and outcome measures of ACOS. Methods: We used data from the National Health and Nutrition Examination Survey (NHANES) from [2007][2008][2009][2010][2011][2012] to determine the population estimates of ACOS in U.S. adults using 2 different definitions of ACOS (ACOS1 =self-reported COPD and current asthma; ACOS2 = spirometric-confirmed COPD [pre-bronchodilator FEV1/FVC <70%] and current asthma) and to describe variation in other factors, such as lung function impairment and health care utilization, by ACOS definitions. Results: Among U.S. adults aged 20 and older, 1.6% had ACOS1, and 1.9% had ACOS2. Both case definitions were similar with regard to symptoms and impairment of lung function. ACOS1 individuals were more likely to have one or more overnight hospital stays relative to those with neither asthma nor COPD, (odds ratio [OR] 3.4, 95% confidence interval [CI] 2.5, 4.6) than ACOS2 (OR 1.6, 95% CI 0.9, 2.9). Conclusions: Different definitions of ACOS in population-based studies affect both estimates of disease prevalence and outcomes related to the disease. These definitions need to be carefully considered in the design of epidemiologic studies and clinical trials. AbstractAbbreviations: asthma-COPD overlap syndrome, ACOS; National Health and Nutrition Examination Survey, NHANES; odds ratio, OR; confidence interval, CI; Global Initiative for Asthma, GINA; Global initiative for chronic Obstructive Lung Disease, GOLD; forced expiratory volume in 1 second, FEV 1 ; forced vital capacity, FVC; fractional exhaled nitric oxide, FeNO; parts per billion, ppb; body mass index, BMI; lower limit of normal, LLN Funding Support: This study was funded by GlaxoSmithKline (Study number WEUSKOP7057). Date of Acceptance: October 28, 2016 Citation: Mannino DM, Gan WQ, Wurst K, Davis KJ. Asthma and chronic obstructive pulmonary disease overlap: The effect of definitions on measures of burden.

Global prevalence of asthma-COPD overlap (ACO) in the general population: a systematic review and meta-analysis

“…The study characteristics of the included studies are summarized in Table 2. In total, we included 27 studies published since 2011, except for one study that published in 1996: twelve from Europe [10, 12, 13, 16, 17, 20, 23, 25, 28–30, 35], nine from the North America (United States and Canada) [11, 15, 18, 21, 26, 27, 32–34], three East Asia (China and Korea) [19, 22, 36], three from the Latin America and 6 low- and middle-income countries and Australia [14, 24, 31]. The majority of the included studies were published after 2015.…”

Prevalence and features of asthma‐COPD overlap in the United States 2007–2012

“…According to international guidelines, COPD is diagnosed only when airflow obstruction is documented by spirometry (11, 12, 13). The only U.S. study that used spirometry defined COPD as Forced Expiratory Volume in 1 second (FEV1) / Forced Vital Capacity (FVC) < 70% pre-bronchodilator administration, instead of the post-bronchodilator as suggested by the GOLD (14). Furthermore, ACO features are yet to be fully described and there is a need to identify biomarkers that differentiate ACO from asthma and COPD (15).…”

Asthma-COPD overlap: current understanding and the utility of experimental models

“…A recent study incorporated elements of this approach by tracking features such as persistent airflow limitation, 40 years of age or older, a history of asthma during early life, and significant smoke exposure (⩾10 pack-years) [40]. Importantly, there remains no global consensus on appropriate diagnostic criteria for ACO, and the implementation of different criteria among epidemiologic studies has produced significant variations in reported statistics for disease prevalence and outcomes [12,42,43]. These limitations are intrinsic to the conventional systems of disease labelling, which may be addressed by incorporating elements of the treatable traits strategy to characterise the complexity and heterogeneity of ACO.…”