Epidemiology and risk factors of asthma-chronic obstructive pulmonary disease overlap in low- and middle-income countries

• Published in: Journal of allergy and clinical immunology Vol. 143; no. 4; pp. 1598 - 1606
• Main Authors: Morgan, Brooks W., Grigsby, Matthew R., Siddharthan, Trishul, Chowdhury, Muhammad, Rubinstein, Adolfo, Gutierrez, Laura, Irazola, Vilma, Miranda, J. Jaime, Bernabe-Ortiz, Antonio, Alam, Dewan, Wise, Robert A., Checkley, William
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-04-2019; Elsevier Limited
• Subjects: ACO; Adult; Age; Aged; Aged, 80 and over; Air flow; Air Pollutants - adverse effects; Air Pollution - adverse effects; Airway management; Asthma; Asthma - epidemiology; asthma-COPD overlap; Biomass; Biomass energy; Chronic obstructive pulmonary disease; COPD; Cross-Sectional Studies; Developing Countries; Environmental Exposure - adverse effects; Epidemiology; Exposure; Female; health outcomes; Health risks; High income; Humans; Hypersensitivity; Illnesses; Low income groups; Lung diseases; Lungs; Male; Middle Aged; Obstructive lung disease; overlap; Population; Population studies; population-based; Prevalence; Pulmonary Disease, Chronic Obstructive - epidemiology; Quality of life; Respiratory diseases; Respiratory function; Respiratory tract; Risk Factors; Smoke; Smoking; Smoking - adverse effects; spirometry; Studies; Thoracic surgery; Tobacco; Tuberculosis; Urbanization; Uganda; Bangladesh; United States > US; Kampala Uganda; risk factors; ATS/ERS; OR; asthma-COPD overlap; LMICs; ACO; population-based; Asthma; epidemiology; health outcomes; FVC; overlap; spirometry; PRISA; LiNK; chronic obstructive pulmonary disease; COPD; BMI
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2018.06.052

Asthma-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.
We aimed to describe the prevalence and risk factors for ACO among adults across 6 low- and middle-income countries (LMICs).
We 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.
The 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).
ACO 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.
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