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.

Small airways obstruction and its risk factors in the Burden of Obstructive Lung Disease (BOLD) study: a multinational cross-sectional study.

BACKGROUND: Small airways obstruction is a common feature of obstructive lung diseases. Research is scarce on small airways obstruction, its global prevalence, and risk factors. We aimed to estimate the prevalence of small airways obstruction, examine the associated risk factors, and compare the findings for two different spirometry parameters. METHODS: The Burden of Obstructive Lung Disease study is a multinational cross-sectional study of 41 municipalities in 34 countries across all WHO regions. Adults aged 40 years or older who were not living in an institution were eligible to participate. To ensure a representative sample, participants were selected from a random sample of the population according to a predefined site-specific sampling strategy. We included participants' data in this study if they completed the core study questionnaire and had acceptable spirometry according to predefined quality criteria. We excluded participants with a contraindication for lung function testing. We defined small airways obstruction as either mean forced expiratory flow rate between 25% and 75% of the forced vital capacity (FEF25-75) less than the lower limit of normal or forced expiratory volume in 3 s to forced vital capacity ratio (FEV3/FVC ratio) less than the lower limit of normal. We estimated the prevalence of pre-bronchodilator (ie, before administration of 200 µg salbutamol) and post-bronchodilator (ie, after administration of 200 µg salbutamol) small airways obstruction for each site. To identify risk factors for small airways obstruction, we performed multivariable regression analyses within each site and pooled estimates using random-effects meta-analysis. FINDINGS: 36 618 participants were recruited between Jan 2, 2003, and Dec 26, 2016. Data were collected from participants at recruitment. Of the recruited participants, 28 604 participants had acceptable spirometry and completed the core study questionnaire. Data were available for 26 443 participants for FEV3/FVC ratio and 25 961 participants for FEF25-75. Of the 26 443 participants included, 12 490 were men and 13 953 were women. Prevalence of pre-bronchodilator small airways obstruction ranged from 5% (34 of 624 participants) in Tartu, Estonia, to 34% (189 of 555 participants) in Mysore, India, for FEF25-75, and for FEV3/FVC ratio it ranged from 5% (31 of 684) in Riyadh, Saudi Arabia, to 31% (287 of 924) in Salzburg, Austria. Prevalence of post-bronchodilator small airways obstruction was universally lower. Risk factors significantly associated with FEV3/FVC ratio less than the lower limit of normal included increasing age, low BMI, active and passive smoking, low level of education, working in a dusty job for more than 10 years, previous tuberculosis, and family history of chronic obstructive pulmonary disease. Results were similar for FEF25-75, except for increasing age, which was associated with reduced odds of small airways obstruction. INTERPRETATION: Despite the wide geographical variation, small airways obstruction is common and more prevalent than chronic airflow obstruction worldwide. Small airways obstruction shows the same risk factors as chronic airflow obstruction. However, further research is required to investigate whether small airways obstruction is also associated with respiratory symptoms and lung function decline. FUNDING: National Heart and Lung Institute and Wellcome Trust. TRANSLATIONS: For the Dutch, Estonian, French, Icelandic, Malay, Marathi, Norwegian, Portuguese, Swedish and Urdu translations of the abstract see Supplementary Materials section.

Prevalence and Population-Attributable Risk for Chronic Airflow Obstruction in a Large Multinational Study.

Rationale: The Global Burden of Disease program identified smoking and ambient and household air pollution as the main drivers of death and disability from chronic obstructive pulmonary disease (COPD). Objectives: To estimate the attributable risk of chronic airflow obstruction (CAO), a quantifiable characteristic of COPD, due to several risk factors. Methods: The Burden of Obstructive Lung Disease study is a cross-sectional study of adults, aged ≥40, in a globally distributed sample of 41 urban and rural sites. Based on data from 28,459 participants, we estimated the prevalence of CAO, defined as a postbronchodilator FEV1-to-FVC ratio less than the lower limit of normal, and the relative risks associated with different risk factors. Local relative risks were estimated using a Bayesian hierarchical model borrowing information from across sites. From these relative risks and the prevalence of risk factors, we estimated local population attributable risks. Measurements and Main Results: The mean prevalence of CAO was 11.2% in men and 8.6% in women. The mean population attributable risk for smoking was 5.1% in men and 2.2% in women. The next most influential risk factors were poor education levels, working in a dusty job for ≥10 years, low body mass index, and a history of tuberculosis. The risk of CAO attributable to the different risk factors varied across sites. Conclusions: Although smoking remains the most important risk factor for CAO, in some areas, poor education, low body mass index, and passive smoking are of greater importance. Dusty occupations and tuberculosis are important risk factors at some sites.

Low prevalence of obstructive lung disease in a suburban population of Malaysia: A BOLD collaborative study.

BACKGROUND AND OBJECTIVE: As a Burden of Obstructive Lung Disease (BOLD) collaboration, we studied the prevalence of chronic obstructive pulmonary disease (COPD) and its associated risk factors in a suburban population in Malaysia. METHODS: Nonhospitalized men or women of age ≥ 40 years from a Penang district were recruited by stratified simple random sampling. Participants completed detailed questionnaires on respiratory symptoms and exposure to COPD risk factors. Prebronchodilator and post-bronchodilator spirometry conducted was standardized across all international BOLD sites in device and data quality control. RESULTS: Of the 1218 individuals recruited for the study, 663 (340 men and 323 women) had complete questionnaire data and acceptable post-bronchodilator spirometry. The estimated population prevalence of Global Initiative for Chronic Obstructive Lung Disease (GOLD) ≥ stage I was 6.5% or 3.4% based on either fixed forced expiratory volume in 1 s/forced vital capacity ratio of <0.7 or National Health and Nutritional Examination Survey-derived lower limit of normal ratio while the prevalence of GOLD ≥ stage II was either 4.6% or 3.1%, respectively. Multivariate logistic regression analysis showed independent association between all stages of COPD with cigarette smoking pack years (adjusted odds ratio per 10-year increase: 1.73; 95% confidence interval: 1.09-2.75), use of biomass fuel for cooking (1.61; 1.10-2.36) and exposure to dusty job (1.50; 1.09-2.06). CONCLUSION: This study represented the first robust population-based epidemiology data on COPD for Malaysia. Compared with other sites globally, our estimated population prevalence was relatively low. In addition to cigarette smoking, use of biomass fuel and exposure to dusty job represented significant risk to the development of COPD.

Characteristics of stable chronic obstructive pulmonary disease patients in the pulmonology clinics of seven Asian cities.

BACKGROUND AND OBJECTIVES: Chronic obstructive pulmonary disease (COPD) is responsible for significant morbidity and mortality worldwide. We evaluated the characteristics of stable COPD patients in the pulmonology clinics of seven Asian cities and also evaluated whether the exposure to biomass fuels and dusty jobs were related to respiratory symptoms, airflow limitation, and quality of life in the COPD patients. METHODS: This cross-sectional observational study recruited 922 COPD patients from seven cities of Asia. The patients underwent spirometry and were administered questionnaires about their exposure to cigarette smoking, biomass fuels, and dusty jobs in addition to respiratory symptoms and health related quality of life. RESULTS: Of the patients, there appeared to be variations from city to city in the history of exposure to biomass fuels and dusty jobs and also in respiratory symptoms of cough, phlegm, wheeze, and dyspnea. These symptoms were more frequent in those COPD patients with a history of exposure to biomass fuels than without and those with a history of exposure to dusty jobs than without (P < 0.01 for all comparisons). Airflow limitation was more severe in those COPD patients with a history of exposure to biomass fuels than without (52.2% predicted versus 55.9% of post-bronchodilator forced expiratory volume in 1 second [FEV(1)], P = 0.009); quality of life was poorer in those with exposure to biomass fuels than without (40.4 versus 36.2 of the St George's Respiratory Questionnaire [SGRQ] total score, P = 0.001). Airflow limitation was more severe in those COPD patients with a history of exposure to dusty jobs than without (51.2% predicted versus 57.3% of post-bronchodilator FEV(1), P < 0.001); quality of life was poorer in those with dusty jobs than without (41.0 versus 34.6 of SGRQ score, P = 0.006). CONCLUSION: In Asian cities, the characteristics of COPD patients vary and the history of exposure to biomass fuels or dusty jobs was related to frequency of symptoms, severe airflow limitation, and poor quality of life.

Time delay and its effect on survival in malaysian patients with non-small cell lung carcinoma.

While evidence indicates that early stage disease has better prognosis, the effect of delay in presentation and treatment of patients with non-small cell lung cancer (NSCLC) on survival is debatable. A retrospective study of 122 Malaysian patients with NSCLC was performed to examine the presentation and treatment delay, and its relation with patient survival. Median (25-75% IQR) interval between onset of symptoms and first hospital consultation (patient delay) and between first hospital consultation and treatment or decision to treat (doctor delay) were 2 (1.0- 5.0) and 1.1 (0.6-2.4) months respectively. The median survival rates in patient delay of <1, 1 to 3, and >3 months were 4.1 (9.9-1.7), 5.1 (10.9-3.2) and 5.7 (12.3-2.1) months respectively (log rank p=0.648), while in doctor delay, <30, 30-60, >60 days, the rates were 4.1 (10.8-1.8), 7.6 (13.7-3.2) and 5.3 (16.0-3.0) months respectively (p=0.557). Most patients presented and were treated in a relatively short time, and delays did not appear to influence survival. This Asian data is consistent with those from Western population, reiterating the need for public health measures that can identify disease early..

Survival in Patients with Non-Small Cell Lung Cancer Who Opted out of Cancer-Specific Therapy.

In Malaysia, many patients opted out of cancer-specific treatment for various reasons. This study was undertaken to investigate the survival rate of patients with stages I to III non-small cell lung cancer (NSCLC) who opted out of treatment, compared with those who accepted treatment. Case records of 119 patients diagnosed with NSCLC between 1996 and 2003 in two urban-based hospitals were retrospectively examined. Survival status was ascertained from follow-up medical clinic records or telephone contact with patients or their next-of-kin. Median (25-75% IQR) survival rate for 79 patients who accepted and 22 patients who opted out of treatment, were 8.6 (16.0-3.7) and 2.2 (3.5-0.8) months respectively [log rank p< 0.001, Kaplan-Meier survival analysis]. Except for proportionately more patients with large cell carcinoma who declined treatment, there was no significant difference between the two groups in relation with age, gender, ethnicity, tumour stage, and time delays between symptom onset and treatment or decision-to-treat. We concluded that there was a small but significant survival benefit in accepting cancer-specific treatment. The findings imply that there is no effective alternative therapy to cancer-specific treatment in improving survival. However, overall prognosis for patients with NSCLC remains dismal.