Prevalence of chronic cough, its risk factors and population attributable risk in the Burden of Obstructive Lung Disease (BOLD) study: a multinational cross-sectional study.

Background: Chronic cough is a common respiratory symptom with an impact on daily activities and quality of life. Global prevalence data are scarce and derive mainly from European and Asian countries and studies with outcomes other than chronic cough. In this study, we aimed to estimate the prevalence of chronic cough across a large number of study sites as well as to identify its main risk factors using a standardised protocol and definition. Methods: We analysed cross-sectional data from 33,983 adults (≥40 years), recruited between Jan 2, 2003 and Dec 26, 2016, in 41 sites (34 countries) from the Burden of Obstructive Lung Disease (BOLD) study. We estimated the prevalence of chronic cough for each site accounting for sampling design. To identify risk factors, we conducted multivariable logistic regression analysis within each site and then pooled estimates using random-effects meta-analysis. We also calculated the population attributable risk (PAR) associated with each of the identifed risk factors. Findings: The prevalence of chronic cough varied from 3% in India (rural Pune) to 24% in the United States of America (Lexington,KY). Chronic cough was more common among females, both current and passive smokers, those working in a dusty job, those with a history of tuberculosis, those who were obese, those with a low level of education and those with hypertension or airflow limitation. The most influential risk factors were current smoking and working in a dusty job. Interpretation: Our findings suggested that the prevalence of chronic cough varies widely across sites in different world regions. Cigarette smoking and exposure to dust in the workplace are its major risk factors. Funding: Wellcome Trust.

Isolated small airways obstruction predicts future chronic airflow obstruction: a multinational longitudinal study.

BACKGROUND: Chronic airflow obstruction is a key characteristic of chronic obstructive pulmonary disease. We investigated whether isolated small airways obstruction is associated with chronic airflow obstruction later in life. METHODS: We used longitudinal data from 3957 participants of the multinational Burden of Obstructive Lung Disease study. We defined isolated small airways obstruction using the prebronchodilator mean forced expiratory flow rate between 25% and 75% of the forced vital capacity (FVC) (FEF25-75) if a result was less than the lower limit of normal (

Research Publications from the ATS MECOR Program in Turkiye.

Background: The American Thoracic Society (ATS) Methods in Epidemiologic, Clinical, and Operations Research (MECOR) Program aims to build research capacity in low and middle-income countries. MECOR has three levels, during which students learn to develop a research protocol and write a manuscript. MECOR Turkiye has been offered every year since 2008. Objective: The aim of this paper is to report the number and impact of published articles generated from research questions developed by students in levels 1, 2, and 3 of the ATS MECOR Program in Turkiye between 2008 and 2018. Methods: We collected the research questions developed in all levels of the ATS MECOR Program in Turkiye between 2008 and 2018. We searched Google Scholar, PubMed, Web of Science, and ResearchGate in April 2022 to see how many of these research questions were published as articles and, if published, in which journals. Results: Of the 176 research questions collected, 49 had been developed in level 1, 82 had been developed in level 2, and 45 had been developed in level 3. Of those 176 research questions, 55 (31.3%) generated articles that were accepted for publication. The frequency of published articles based on MECOR-developed research questions increased linearly as the course level in which they were developed increased (18.4% in level 1, 30% in level 2, 46.7% in level 3; P = 0.012; linear-by-linear association, P = 0.003). The median time from the development of the research question to publication was three years overall and did not differ significantly among the course levels (P = 0.36). Of the research questions developed, 43 were published in Science Citation Index or Science Citation Index Expanded-indexed journals. Conclusion: Acceptance of an article for publication is one way to measure the impact of the ATS MECOR Program. Our data describe significant research output among our participants, which increases with their length of participation in the program.

Chronic airflow obstruction attributable to poverty in the multinational Burden of Obstructive Lung Disease (BOLD) study.

Poverty is strongly associated with all-cause and chronic obstructive pulmonary disease (COPD) mortality. Less is known about the contribution of poverty to spirometrically defined chronic airflow obstruction (CAO)-a key characteristic of COPD. Using cross-sectional data from an asset-based questionnaire to define poverty in 21 sites of the Burden of Obstructive Lung Disease study, we estimated the risk of CAO attributable to poverty. Up to 6% of the population over 40 years had CAO attributable to poverty. Understanding the relationship between poverty and CAO might suggest ways to improve lung health, especially in low-income and middle-income countries.

Altitude and COPD prevalence: analysis of the PREPOCOL-PLATINO-BOLD-EPI-SCAN study.

BACKGROUND: COPD prevalence is highly variable and geographical altitude has been linked to it, yet with conflicting results. We aimed to investigate this association, considering well known risk factors. METHODS: A pooled analysis of individual data from the PREPOCOL-PLATINO-BOLD-EPI-SCAN studies was used to disentangle the population effect of geographical altitude on COPD prevalence. Post-bronchodilator FEV1/FVC below the lower limit of normal defined airflow limitation consistent with COPD. High altitude was defined as >1500 m above sea level. Undiagnosed COPD was considered when participants had airflow limitation but did not report a prior diagnosis of COPD. RESULTS: Among 30,874 participants aged 56.1 ± 11.3 years from 44 sites worldwide, 55.8% were women, 49.6% never-smokers, and 12.9% (3978 subjects) were residing above 1500 m. COPD prevalence was significantly lower in participants living at high altitude with a prevalence of 8.5% compared to 9.9%, respectively (p < 0.005). However, known risk factors were significantly less frequent at high altitude. Hence, in the adjusted multivariate analysis, altitude itself had no significant influence on COPD prevalence. Living at high altitude, however, was associated with a significantly increased risk of undiagnosed COPD. Furthermore, subjects with airflow limitation living at high altitude reported significantly less respiratory symptoms compared to subjects residing at lower altitude. CONCLUSION: Living at high altitude is not associated with a difference in COPD prevalence after accounting for individual risk factors. However, high altitude itself was associated with an increased risk of undiagnosed COPD.

The association between chronic airflow obstruction and poverty in 12 sites of the multinational BOLD study.

Poverty is strongly associated with mortality from COPD, but little is known of its relation to airflow obstruction.In a cross-sectional study of adults aged ≥40 years from 12 sites (N=9255), participating in the Burden of Obstructive Lung Disease (BOLD) study, poverty was evaluated using a wealth score (0-10) based on household assets. Obstruction, measured as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) (%) after administration of 200 µg salbutamol, and prevalence of FEV1/FVC

Chronic Airflow Obstruction in a Black African Population: Results of BOLD Study, Ile-Ife, Nigeria.

Global estimates suggest that Chronic Obstructive Pulmonary Disease (COPD) is emerging as a leading cause of death in developing countries but there are few spirometry-based general population data on its prevalence and risk factors in sub-Saharan Africa. We used the Burden of Obstructive Lung Disease (BOLD) protocol to select a representative sample of adults aged 40 years and above in Ile-Ife, Nigeria. All the participants underwent spirometry and provided information on smoking history, biomass and occupational exposures as well as diagnosed respiratory diseases and symptoms. Chronic Airflow Obstruction (CAO) was defined as the ratio of post-bronchodilator (BD) one second Forced Expiratory Volume (FEV1) to Forced Vital Capacity (FVC) below the lower limit of normal (LLN) of the population distribution for FEV1/FVC. The overall prevalence of obstruction (post-BD FEV1/FVC < LLN) was 7.7% (2.7% above LLN) using Global Lung Function Initiative (GLI) equations. It was associated with few respiratory symptoms; 0.3% reported a previous doctor-diagnosed chronic bronchitis, emphysema or COPD. Independent predictors included a lack of education (OR 2.5, 95% CI: 1.0, 6.4) and a diagnosis of either TB (OR 23.4, 95% CI: 2.0, 278.6) or asthma (OR 35.4, 95%CI: 4.9, 255.8). There was no association with the use of firewood or coal for cooking or heating. The vast majority of this population (89%) are never smokers. We conclude that the prevalence of CAO is low in Ile-Ife, Nigeria and unrelated to biomass exposure. The key independent predictors are poor education, and previous diagnosis of tuberculosis or asthma.

Burden of obstructive lung disease study in Tehran: Prevalence and risk factors of chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) was ranked the sixth-most common cause of death worldwide in 1990, but now it is the third-most common cause. The goal of the present study was to assess the prevalence and determine the causes and risk factors of COPD in Tehran. MATERIALS AND METHODS: This study followed a stratified cluster sampling strategy with proportional allocation within strata. The target population was all non-institutionalized inhabitants, aged 18 to 40 in one group and over 40 in another who resided in Tehran in 2013. The core questionnaire was developed from pre-existing validated questionnaires that had already been used in multi-national studies. The single most important outcome measure obtained as part of this protocol was spirometry before and after the administration of 200 mg (two puffs) of salbutamol. RESULTS: The most commonly reported respiratory symptoms were: sputum production in 291 patients (16.2%) [95% confidence interval (CI): 14.5-17.9%], chronic cough in 171 (9.5%) (95% CI: 8.2-10.9%), wheezing in 377 (21.0%) (95%CI: 19.1-22.9%) and dyspnea in 388 patients (21.6%) (95% CI: 19.7-23.5%). The overall COPD prevalence defined by the post-bronchodilator spirometric functional criteria was 9.2%. This value in men (10.1%) was higher than in women (8.5%); the prevalence was significantly higher in subjects aged over 55 years (P ≤ 0.002). The prevalence of COPD was strongly dependent on smoking status, especially in ex-smokers, and increased considerably with age. 69% of patients with COPD were non-smoker. CONCLUSION: The high prevalence of verified COPD, a great deal of which was undiagnosed before by a physician, highlights the necessity of raising awareness of this disease among health professionals, and use of spirometry in the primary care setting. A future cross-sectional and prospective cohort study should be performed to explore all risk factors and their impact on decline in lung function and worsening of respiratory symptoms especially in non-smokers.

Tuberculosis associates with both airflow obstruction and low lung function: BOLD results.

In small studies and cases series, a history of tuberculosis has been associated with both airflow obstruction, which is characteristic of chronic obstructive pulmonary disease, and restrictive patterns on spirometry. The objective of the present study was to assess the association between a history of tuberculosis and airflow obstruction and spirometric abnormalities in adults.The study was performed in adults, aged 40 years and above, who took part in the multicentre, cross-sectional, general population-based Burden of Obstructive Lung Disease study, and had provided acceptable post-bronchodilator spirometry measurements and information on a history of tuberculosis. The associations between a history of tuberculosis and airflow obstruction and spirometric restriction were assessed within each participating centre, and estimates combined using meta-analysis. These estimates were stratified by high- and low/middle-income countries, according to gross national income.A self-reported history of tuberculosis was associated with airflow obstruction (adjusted odds ratio 2.51, 95% CI 1.83-3.42) and spirometric restriction (adjusted odds ratio 2.13, 95% CI 1.42-3.19).A history of tuberculosis was associated with both airflow obstruction and spirometric restriction, and should be considered as a potentially important cause of obstructive disease and low lung function, particularly where tuberculosis is common.

Determinants of underdiagnosis of COPD in national and international surveys.

BACKGROUND: COPD ranks within the top three causes of mortality in the global burden of disease, yet it remains largely underdiagnosed. We assessed the underdiagnosis of COPD and its determinants in national and international surveys of general populations. METHODS: We analyzed representative samples of adults aged ≥ 40 years randomly selected from well-defined administrative areas worldwide (44 sites from 27 countries). Postbronchodilator FEV1/FVC < lower limit of normal (LLN) was used to define chronic airflow limitation consistent with COPD. Undiagnosed COPD was considered when participants had postbronchodilator FEV1/FVC < LLN but were not given a diagnosis of COPD. RESULTS: Among 30,874 participants with a mean age of 56 years, 55.8% were women, and 22.9% were current smokers. Population prevalence of (spirometrically defined) COPD ranged from 3.6% in Barranquilla, Colombia, to 19.0% in Cape Town, South Africa. Only 26.4% reported a previous lung function test, and only 5.0% reported a previous diagnosis of COPD, whereas 9.7% had a postbronchodilator FEV1/FVC < LLN. Overall, 81.4% of (spirometrically defined) COPD cases were undiagnosed, with the highest rate in Ile-Ife, Nigeria (98.3%) and the lowest rate in Lexington, Kentucky (50.0%). In multivariate analysis, a greater probability of underdiagnosis of COPD was associated with male sex, younger age, never and current smoking, lower education, no previous spirometry, and less severe airflow limitation. CONCLUSIONS: Even with substantial heterogeneity in COPD prevalence, COPD underdiagnosis is universally high. Because effective management strategies are available for COPD, spirometry can help in the diagnosis of COPD at a stage when treatment will lead to better outcomes and improved quality of life.

Symptomatic chronic obstructive pulmonary disease in clinical trials and in a population-based study.

PURPOSE: Evidence-based medicine promotes the current best evidence from clinical trials to guide decisions for individual patients. We assessed whether chronic obstructive pulmonary disease (COPD) patients included in exercise training studies and pharmacologic trials match those from a non-selected COPD target population sample. METHODS: Exercise training studies were identified in a literature search. Towards a Revolution in COPD Health (TORCH) and Understanding Potential Long-Term Impacts on Function with Tiotropium (UPLIFT) were chosen to represent pharmacologic trials. Burden of Obstructive Lung Disease (BOLD) data were used to characterize target COPD population (BOLD target), defined as the presence of dyspnea (modified Medical Research Council ≥2) and non-reversible airway obstruction (post-bronchodilator FEV1/FVC ≤0.7 and FEV1% predicted ≤70 %). RESULTS: Overall 240 exercise training studies with 13,901, TORCH and UPLIFT with 12,105, and BOLD with 16,218 participants were evaluated. Males were overrepresented in exercise training studies (67.5%) and pharmacologic trials (TORCH 75.8%; UPLIFT 74.6%), whereas in BOLD target 55.8% were males (p < 0.001). In exercise training studies, 7.2% were never-smokers, 0.0% in TORCH and UPLIFT, but 36.0% in BOLD target (p < 0.001). Subjects with cardiac comorbidity were excluded from 75.4% of exercise training studies, entirely from TORCH and UPLIFT, but comprised 24.5% of BOLD target. CONCLUSIONS: COPD patients recruited in exercise training studies and in pharmacologic trials differ from target population of symptomatic COPD. Females, never-smokers, and patients with cardiac comorbidities are more likely excluded from the clinical trials.

Burden of obstructive lung disease study in tehran: research design and lung spirometry protocol.

BACKGROUND: Chronic obstructive pulmonary diseases (COPD) are planned to rank fifth in burden of disease and third with respect to mortality by 2020. Carrying out research regarding different aspects of COPD is mentioned as important health priorities by academic institutions and governments. The burden of lung disease (BOLD) Initiative was designed a decade ago to develop robust models that can be used to estimate the prevalence and current and future economic burden of COPD. The goal of the present project is to describe the prevalence and determining the causes and risk factors of COPD in the population of Tehran city. METHODS: This cross-sectional study follows a stratified cluster sampling strategy with proportional allocation within strata. The target population is all noninstitutionalized inhabitants, aged 18-40 in one group and over 40 in another, who inhabit in Tehran city. The stratification of the sample according to the 22 municipal districts of Tehran is incorporated in the sampling process. Proportional to the number of households in the 22 districts, the appropriate number of clusters is weighted according to each district. For each cluster, a team of three members approaches the index household, which is specified through the aforementioned random selection of clusters, and continues the enumeration in 10 neighbor households in a systematic manner. RESULTS: As a study protocol, there are no specific results to present; our purpose is to share our design with the scientific body. CONCLUSIONS: We expect that findings from the BOLD study in Tehran will show the status of COPD and its causes in the community.

Respiratory risks from household air pollution in low and middle income countries.

A third of the world's population uses solid fuel derived from plant material (biomass) or coal for cooking, heating, or lighting. These fuels are smoky, often used in an open fire or simple stove with incomplete combustion, and result in a large amount of household air pollution when smoke is poorly vented. Air pollution is the biggest environmental cause of death worldwide, with household air pollution accounting for about 3·5-4 million deaths every year. Women and children living in severe poverty have the greatest exposures to household air pollution. In this Commission, we review evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases. Respiratory infections (comprising both upper and lower respiratory tract infections with viruses, bacteria, and mycobacteria) have all been associated with exposure to household air pollution. Respiratory tract cancers, including both nasopharyngeal cancer and lung cancer, are strongly associated with pollution from coal burning and further data are needed about other solid fuels. Chronic lung diseases, including chronic obstructive pulmonary disease and bronchiectasis in women, are associated with solid fuel use for cooking, and the damaging effects of exposure to household air pollution in early life on lung development are yet to be fully described. We also review appropriate ways to measure exposure to household air pollution, as well as study design issues and potential effective interventions to prevent these disease burdens. Measurement of household air pollution needs individual, rather than fixed in place, monitoring because exposure varies by age, gender, location, and household role. Women and children are particularly susceptible to the toxic effects of pollution and are exposed to the highest concentrations. Interventions should target these high-risk groups and be of sufficient quality to make the air clean. To make clean energy available to all people is the long-term goal, with an intermediate solution being to make available energy that is clean enough to have a health impact.

Chronic obstructive pulmonary disease mortality and prevalence: the associations with smoking and poverty--a BOLD analysis.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a commonly reported cause of death and associated with smoking. However, COPD mortality is high in poor countries with low smoking rates. Spirometric restriction predicts mortality better than airflow obstruction, suggesting that the prevalence of restriction could explain mortality rates attributed to COPD. We have studied associations between mortality from COPD and low lung function, and between both lung function and death rates and cigarette consumption and gross national income per capita (GNI). METHODS: National COPD mortality rates were regressed against the prevalence of airflow obstruction and spirometric restriction in 22 Burden of Obstructive Lung Disease (BOLD) study sites and against GNI, and national smoking prevalence. The prevalence of airflow obstruction and spirometric restriction in the BOLD sites were regressed against GNI and mean pack years smoked. RESULTS: National COPD mortality rates were more strongly associated with spirometric restriction in the BOLD sites (<60 years: men rs=0.73, p=0.0001; women rs=0.90, p<0.0001; 60+ years: men rs=0.63, p=0.0022; women rs=0.37, p=0.1) than obstruction (<60 years: men rs=0.28, p=0.20; women rs=0.17, p<0.46; 60+ years: men rs=0.28, p=0.23; women rs=0.22, p=0.33). Obstruction increased with mean pack years smoked, but COPD mortality fell with increased cigarette consumption and rose rapidly as GNI fell below US$15 000. Prevalence of restriction was not associated with smoking but also increased rapidly as GNI fell below US$15 000. CONCLUSIONS: Smoking remains the single most important cause of obstruction but a high prevalence of restriction associated with poverty could explain the high 'COPD' mortality in poor countries.

Prevalence of COPD and tobacco smoking in Tunisia--results from the BOLD study.

In Tunisia, there is a paucity of population-based data on Chronic Obstructive Pulmonary Disease (COPD) prevalence. To address this problem, we estimated the prevalence of COPD following the Burden of Lung Disease Initiative. We surveyed 807 adults aged 40+ years and have collected information on respiratory history and symptoms, risk factors for COPD and quality of life. Post-bronchodilator spirometry was performed and COPD and its stages were defined according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Six hundred and sixty one (661) subjects were included in the final analysis. The prevalence of GOLD Stage I and II or higher COPD were 7.8% and 4.2%, respectively (Lower Limit of Normal modified stage I and II or higher COPD prevalence were 5.3% and 3.8%, respectively). COPD was more common in subjects aged 70+ years and in those with a BMI < 20 kg/m2. Prevalence of stage I+ COPD was 2.3% in <10 pack years smoked and 16.1% in 20+ pack years smoked. Only 3.5% of participants reported doctor-diagnosed COPD. In this Tunisian population, the prevalence of COPD is higher than reported before and higher than self-reported doctor-diagnosed COPD. In subjects with COPD, age is a much more powerful predictor of lung function than smoking.