Original ArticleEpidemiologicalAirflow Obstruction in Never Smokers in Five Latin American Cities: The PLATINO Study
Introduction
Chronic obstructive pulmonary disease (COPD) is a leading cause of death and chronic morbidity with increasing worldwide prevalence 1, 2, 3, 4, 5, 6. Research in COPD has been centered on smokers except for a few studies in developed countries 7, 8, 9, 10, 11, 12, 13, 14 and some in developing countries related mostly to exposure to biomass smoke. Although incidence of COPD is mainly related to smokers, the proportion varies 8, 11, 12. For example, in a recent review (see Reference 12), from 9–31% of COPD in males and 22–86% in females were never smokers. Well-known causes of irreversible or poorly reversible airflow obstruction, for example, occupational exposures, bronchiectasis, alpha-1-antiprotease deficiency, chronic asthma, exposure to biomass smoke during cooking, and previous tuberculosis 12, 15, 16 as well as the putative but less important factors such as diet, air pollution or passive smoking (17) were recently reviewed (8). In two cross-sectional studies, COPD in never smokers was more common in older age, in those with a medical diagnosis of asthma and subjects with a lower educational level 10, 11. In the BOLD (Burden of Obstructive Lung Disease) study, COPD in never smokers was more common in women and in individuals with lower education (11), whereas in China, in never smokers, COPD was associated with male gender, passive smoking, exposure to solid fuel smoke during cooking, and childhood respiratory disease or a family history of respiratory disease (10). The Proyecto Latinoamericano de Investigación en Obstrucción Pulmonar (PLATINO) study offers an additional opportunity to explore this important group of COPD subjects in never smokers in a large multicenter population-based sample from five Latin American cities with high participation and robust, well-established methods 6, 18. The aims of this study were therefore to describe risk factors for irreversible airflow obstruction (COPD) in never smokers as well as differences with ever smokers including subjects’ perception of general health status, degree of breathlessness and physical activity limitation.
Section snippets
Patients and Methods
Details of the selection method and population sample size of PLATINO have been previously published (18). Multistage cluster sampling was used to obtain a representative sample of subjects aged 40 years or more from the metropolitan area of each of five large Latin American cities: Santiago, Caracas, São Paulo, Montevideo and Mexico City. The study protocol was approved by the ethics committee of each site and all participants provided signed informed consent.
Participants completed a
Results
From a total of 6,711 eligible subjects in all locations, 5,571 individuals completed questionnaires and 5,315 spirometry tests were obtained. Among this population, 2278 (43%) were never smokers and 3036 ever smokers (Table 1). In univariate comparisons, never smokers were more likely female, older, with higher body mass index and spirometric function and with less respiratory symptoms than ever smokers. Airflow obstruction was more common in ever smokers independent of the definition used (
Discussion
This study confirms a significant proportion (26%) of irreversible airflow obstruction (COPD) occurring in never smokers either defined as GOLD stages 2–4 or an FEV1 and FEV1/FVC below the LLN. Important differences in the expression of COPD in a population-based sample were derived from the smoking status. Never smokers were older, more often female, medical diagnosis of asthma, fewer comorbidities and symptoms, better lung function, better quality of life, better response to bronchodilators
Acknowledgments
We acknowledge the Asociación Latinoamericana de Tórax (ALAT) for its support to the PLATINO study and to Boehringer Ingelheim GmbH for funding the study.
Advisory Committee Members are Sonia Buist, William Vollmer. Executive Committee members are Carlos Torres, Juan Luna, and Carmen Lisboa.
PLATINO team (in addition to main authors): Maria Márquez, Maria Blanco, Pedro Hallal, Fernanda Rosa, Aquiles Camelier, Francisco Franco, Dolores Moreno, and Julio Pertuzé.
Conflicts Of Interest: None declared
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For the PLATINO Team. Members listed at end of paper