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.

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.

Case-finding options for COPD: results from the Burden of Obstructive Lung Disease study.

This study aimed to compare strategies for chronic obstructive pulmonary disease (COPD) case finding using data from the Burden of Obstructive Lung Disease study. Population-based samples of adults aged ≥40 yrs (n = 9,390) from 14 countries completed a questionnaire and spirometry. We compared the screening efficiency of differently staged algorithms that used questionnaire data and/or peak expiratory flow (PEF) data to identify persons at risk for COPD and, hence, needing confirmatory spirometry. Separate algorithms were fitted for moderate/severe COPD and for severe COPD. We estimated the cost of each algorithm in 1,000 people. For moderate/severe COPD, use of questionnaire data alone permitted high sensitivity (97%) but required confirmatory spirometry in 80% of participants. Use of PEF necessitated confirmatory spirometry in only 19-22% of subjects, with 83-84% sensitivity. For severe COPD, use of PEF achieved 91-93% sensitivity, requiring confirmatory spirometry in <9% of participants. Cost analysis suggested that a staged screening algorithm using only PEF initially, followed by confirmatory spirometry as needed, was the most cost-effective case-finding strategy. Our results support the use of PEF as a simple, cost-effective initial screening tool for conducting COPD case-finding in adults aged ≥40 yrs. These findings should be validated in real-world settings such as the primary care environment.

Worldwide patterns of bronchodilator responsiveness: results from the Burden of Obstructive Lung Disease study.

RATIONALE: Criteria for a clinically significant bronchodilator response (BDR) are mainly based on studies in patients with obstructive lung diseases. Little is known about the BDR in healthy general populations, and even less about the worldwide patterns. METHODS: 10 360 adults aged 40 years and older from 14 countries in North America, Europe, Africa and Asia participated in the Burden of Obstructive Lung Disease study. Spirometry was used before and after an inhaled bronchodilator to determine the distribution of the BDR in population-based samples of healthy non-smokers and individuals with airflow obstruction. RESULTS: In 3922 healthy never smokers, the weighted pooled estimate of the 95th percentiles (95% CI) for bronchodilator response were 284 ml (263 to 305) absolute change in forced expiratory volume in 1 s from baseline (ΔFEV(1)); 12.0% (11.2% to 12.8%) change relative to initial value (%ΔFEV(1i)); and 10.0% (9.5% to 10.5%) change relative to predicted value (%ΔFEV(1p)). The corresponding mean changes in forced vital capacity (FVC) were 322 ml (271 to 373) absolute change from baseline (ΔFVC); 10.5% (8.9% to 12.0%) change relative to initial value (ΔFVC(i)); and 9.2% (7.9% to 10.5%) change relative to predicted value (ΔFVC(p)). The proportion who exceeded the above threshold values in the subgroup with spirometrically defined Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2 and higher (FEV(1)/FVC <0.7 and FEV(1)% predicted <80%) were 11.1%, 30.8% and 12.9% respectively for the FEV(1)-based thresholds and 22.6%, 28.6% and 22.1% respectively for the FVC-based thresholds. CONCLUSIONS: The results provide reference values for bronchodilator responses worldwide that confirm guideline estimates for a clinically significant level of BDR in bronchodilator testing.

Risk factors for COPD spirometrically defined from the lower limit of normal in the BOLD project.

Chronic obstructive pulmonary disease (COPD) is predicted to become the third most common cause of death and disability worldwide by 2020. The prevalence of COPD defined by the lower limit of normal was estimated using high-quality spirometry in surveys of 14 populations aged ≥ 40 yrs. The strength and consistency of associations were assessed using random effects meta-analysis. Pack-years of smoking were associated with risk of COPD at each site. After adjusting for this effect, we still observed significant associations of COPD risk with age (OR 1.52 for a 10 yr age difference, 95% CI 1.35-1.71), body mass index in obese compared with normal weight (OR 0.50, 95% CI 0.37-0.67), level of education completed (OR 0.76, 95% CI 0.67-0.87), hospitalisation with a respiratory problem before age 10 yrs (OR 2.35, 95% CI 1.42-3.91), passive cigarette smoke exposure (OR 1.24, 95% CI 1.05-1.47), tuberculosis (OR 1.78, 95%CI 1.17-2.72) and a family history of COPD (OR 1.50, 95% CI 1.19-1.90). Although smoking is the most important risk factor for COPD, other risk factors are also important. More research is required to elucidate relevant risk factors in low- and middle-income countries where the greatest impact of COPD will occur.

Systems for the management of respiratory disease in primary care--an international series: South Africa.

INTRODUCTION: Progress to democracy in South Africa in 1994 was followed by the adoption of a primary health care approach with free access for all. State health facilities serve 80% of the population, and a private sector comprising general practitioners, specialists and private hospitals, serves the remainder. NATIONAL POLICIES AND MODELS: There are national prescribing guidelines for common diseases, and these specify the medicines on the Essential Drugs List that are available at primary care facilities for respiratory diseases including asthma, COPD, pneumonia and tuberculosis. EPIDEMIOLOGY: Asthma prevalence is average among children (13%) but morbidity is high. COPD rates are high owing to concurrent risk factors of smoking (in both men and women), occupational exposures, biomass fuel use and previous lung infections including tuberculosis. Tuberculosis and HIV are rampant, and together with pneumococcal co-infection account for considerable mortality. ACCESS TO CARE: Primary care facilities are within reach of most communities, but major barriers to care include loss of income, waiting times in clinics, cost of transportation, and inconvenient hours. FACILITIES AVAILABLE: The country is divided into districts each served by a hospital, several community health centres and many fixed or mobile clinics. The latter provide predominantly nurse-led care by nurse practitioners with additional qualifications. Some clinics and most community health centres are served by doctors. Referrals are made to secondary and tertiary hospitals served by specialists. FUTURE: Innovations to address staff shortages include the creation of the specialty of family medicine for physicians and development of the clinical associate who is trained to perform a limited clinical role, as well as in-service on-site training of nurses through programmes of integrated care for infectious and chronic diseases. There is an urgent need to address low staff morale and medical migration resulting from a decade of poor leadership and AIDS denialism. CONCLUSIONS: The structures and policies for primary care in South Africa provide some grounds for optimism that services may begin to match the promise of quality care for all, but the burden of disease and resource constraints - particularly in terms of qualified personnel - mitigate against an early delivery of this promise.

Association between passive smoking and infection with Mycobacterium tuberculosis in children.

OBJECTIVE: Tuberculosis and smoking are both significant public health problems. The association between passive smoking and Mycobacterium tuberculosis infection is not well documented. The objective of this study was to examine the influence of passive smoking on M. tuberculosis infection in children. METHODS: A community survey was conducted in 15% of addresses in 2 adjacent low-income suburbs in Cape Town, South Africa. All children (< 15 years of age) and their adult household members residing at these addresses were included in the study. Children underwent tuberculin skin testing. An induration of > or = 10 mm was considered to define M. tuberculosis infection. Passive smoking was defined as living in the household with at least 1 adult who smoked for at least 1 year. Random-effects logistic regression analysis was performed, and odds ratios were adjusted for age, presence of a patient with tuberculosis in the household, average household income, and clustering at the household level. RESULTS: Of 1344 children, 432 (32%) had a positive tuberculin skin test. Passive smoking was significantly associated with M. tuberculosis infection in the unadjusted analyses but not in the adjusted analyses. In the 172 households with a patient with tuberculosis, passive smoking was significantly associated with a positive tuberculin skin test but not in the 492 households without a patient with tuberculosis. CONCLUSIONS: Passive smoking is associated with M. tuberculosis infection in children living in a household with a patient with tuberculosis. More studies are needed to confirm this observation, but the possible association is a cause of great concern, considering the high prevalence of smoking and tuberculosis in most developing countries.

Lung diseases in South Africa: an overview.

The profile of both infectious and non-infectious lung diseases in South Africa over the past century reflects prevailing sociopolitical and economic forces. The lung, perhaps more than any other organ system is influenced by poverty, occupation and personal habits. These influences are seen in the association between tuberculosis and pneumoconiosis first described in miners, the increasing prevalence of asthma and smoking-related chronic obstructive pulmonary disease, and the current dual epidemics of tuberculosis and infections associated with the human immunodeficiency virus (HIV). The global prediction for developing countries is that by the year 2020 respiratory diseases (including infections) will account for a large majority of deaths and a considerable burden of disability adjusted life years. The country-wide Demographic and Health Surveys of 1998 and 2003 have provided data on symptom prevalence in South Africa. The Lung Health Survey 2002 performed in Cape Town provides disease prevalence and has identified complex interactions between causative factors and disease. Consistent and biologically plausible associations between smoking and susceptibility to tuberculosis and pneumonia in HIV-infected patients have been reported. These findings are relevant both to the planners of public health interventions, and to researchers exploring disease mechanisms and potential remedies.