• Brooks W Morgan, Matthew R Grigsby, Trishul Siddharthan, Muhammad Chowdhury, Adolfo Rubinstein, Laura Gutierrez, Vilma Irazola, J Jaime Miranda, Antonio Bernabe-Ortiz, Dewan Alam, Robert A Wise, and William Checkley.
• Division of Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Md; Center for Global Non-Communicable Diseases, School of Medicine, Johns Hopkins University, Baltimore, Md.
• J. Allergy Clin. Immunol. 2019 Apr 1; 143 (4): 1598-1606.

BackgroundAsthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) represents the confluence of bronchial airway hyperreactivity and chronic airflow limitation and has been described as leading to worse lung function and quality of life than found with either singular disease process.ObjectiveWe aimed to describe the prevalence and risk factors for ACO among adults across 6 low- and middle-income countries (LMICs).MethodsWe compiled cross-sectional data for 11,923 participants aged 35 to 92 years from 4 population-based studies in 12 settings. We defined COPD as postbronchodilator FEV1/forced vital capacity ratio below the lower limit of normal, asthma as wheeze or medication use in 12 months or self-reported physician diagnosis, and ACO as having both.ResultsThe prevalence of ACO was 3.8% (0% in rural Puno, Peru, to 7.8% in Matlab, Bangladesh). The odds of having ACO were higher with household exposure to biomass fuel smoke (odds ratio [OR], 1.48; 95% CI, 0.98-2.23), smoking tobacco (OR, 1.28 per 10 pack-years; 95% CI, 1.22-1.34), and having primary or less education (OR, 1.35; 95% CI, 1.07-1.70) as compared to nonobstructed nonasthma individuals. ACO was associated with severe obstruction (FEV1 %, <50; 31.6% of ACO vs 10.9% of COPD alone) and severe spirometric deficits compared with participants with asthma (-1.61 z scores FEV1; 95% CI, -1.48 to -1.75) or COPD alone (-0.94 z scores; 95% CI, -0.78 to -1.10).ConclusionsACO may be as prevalent and more severe in LMICs than has been reported in high-income settings. Exposure to biomass fuel smoke may be an overlooked risk factor, and we favor diagnostic criteria for ACO that include environmental exposures common to LMICs.Copyright © 2018 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

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