We searched PubMed (January, 1995–July, 2009) using the search terms “COPD and prevalence”, “COPD and risk factors”, “COPD and occupation”, “COPD and air pollution”, “COPD and tuberculosis”, and “COPD and respiratory-tract infection”. We focused on reports published in the past 5 years, but did not exclude frequently referenced and highly regarded reports published more than 5 years ago. We also searched reference lists of reports identified by this search strategy and selected those we
ReviewChronic obstructive pulmonary disease in non-smokers
Introduction
Chronic obstructive pulmonary disease (COPD) is characterised by progressive airflow obstruction and destruction of lung parenchyma, and is caused by chronic exposure of genetically susceptible individuals to environmental factors. Tobacco smoking was associated with risk of COPD as early as the 1950s;1, 2 smoking was established as a causative risk factor by the findings of Fletcher and Peto's3 8-year prospective study of 792 men, and the larger and longer Framingham cohort offspring study confirmed these results.4 Consequently, later research has focused on smoking as the most important risk factor for COPD; several prevalence studies have been done solely in smokers,5, 6 and most clinical trials in COPD recruit only smokers with at least 20 pack-years of cigarette smoking exposure.
However, in the past decade and especially the past 5 years, results from a growing number of published studies have suggested that risk factors other than smoking are strongly associated with COPD. These factors include exposure to indoor and outdoor air pollutants, workplace exposure to dust and fumes, history of repeated lower respiratory-tract infections during childhood, history of pulmonary tuberculosis, chronic asthma, intrauterine growth retardation, poor nourishment, and poor socioeconomic status.
Section snippets
Evidence of COPD in non-smokers
Phillips7 reported that risk factors other than tobacco smoking were associated with COPD in 1963, and previously Fairbairn8 had reported that outdoor air pollution was an important risk factor. Overwhelming interest in smoking as the major risk factor has overshadowed the importance of non-smoking causes. However, Husman and colleagues9 associated occupation with COPD in 1987 in their 6-year study of Finnish farmers and non-farmers, which showed that a higher proportion of farmers (2·7%) than
Use of biomass fuel
Worldwide, about 50% of all households and 90% of rural households use biomass fuel (wood, charcoal, other vegetable matter, and animal dung) and coal as their main source of domestic energy. About 3 billion people worldwide are exposed to smoke from biomass fuel compared with 1·01 billion people who smoke tobacco, suggesting that exposure to biomass smoke might be the most important global risk factor for COPD.34 About 50% of deaths from COPD in developing countries are attributable to biomass
Occupational exposures
Findings from early studies reported that exposure to toxic gases in the workplace,65 grain dust in farms,66 and dust and fumes in factories67 was strongly associated with COPD. In 2003, results of a systematic epidemiological review into occupational factors associated with COPD by the American Thoracic Society showed that about 15% of COPD cases might be attributable to workplace exposure;68 and a subsequent follow-up provided similar estimates.69
In a study of 1258 adults older than 40 years,
Pulmonary tuberculosis
Pulmonary tuberculosis is associated with chronic airflow obstruction, especially the COPD phenotype, at diagnosis,78, 79 during treatment,80 and several years after treatment has ended.81 Such infection is associated with airway fibrosis, and the immune response to mycobacteria can result in airway inflammation, which is characteristic of COPD. The degree of airflow obstruction is correlated with the extent of disease assessed by radiography, sputum production, and length of time after
Chronic asthma
In 1961, Orie and colleagues85 postulated that asthma and COPD share a common background, and differentiation into each disease can be modulated by environmental and host factors. Although this hypothesis is unresolved,86 chronic airway inflammation and airflow obstruction in individuals with asthma and increased airway hyper-responsiveness might cause lung remodelling from thickening and fibrosis of the airway walls.87 This remodelling could result in irreversible and progressive airflow
Outdoor air pollution
The contribution of outdoor air pollution to COPD was investigated in 1958 in UK postmen—the prevalence of COPD was higher in those working in more polluted areas than in those working in areas with less pollution, and the association was independent of smoking.8 Results of a later study showed reduced lung function in postmen who worked in more polluted cities than in those who worked in less polluted areas.94 These findings have been reinforced by studies in the general population in the UK95
Socioeconomic status
Poor socioeconomic status is a risk factor independently associated with COPD, and is likely to be indicative of other factors such as intrauterine growth retardation, poor nutrition (low intake of antioxidants) and housing conditions, childhood respiratory-tract infections, and exposure to tobacco smoke, biomass smoke and other indoor air pollutants, and occupational risks. These factors might collectively contribute to the risk of COPD. Socioeconomic status has been shown to have a
Population-attributable risk factors
Non-smoking causes of COPD were conventionally estimated to contribute to a small proportion—10–15%—of cases in developed countries, but results of later studies suggest that the true contribution is much higher. Findings from the Swedish OLIN103 and US NHANES III104 studies reported that the population-attributable risk of COPD from smoking was 45% and 44%, respectively, indicating that more than half of COPD cases were due to non-smoking causes. In the BOLD study105 of the prevalence of COPD
Does COPD in never-smokers have a different phenotype?
Very few studies have investigated the non-smoking phenotype of COPD or made comparisons with the smoking phenotype. Ramírez-Venegas and colleagues106 reported that Mexican women who had COPD and had been exposed to smoke from biomass fuel, had similar clinical characteristics, quality of life, and mortality to those with COPD due to tobacco smoking. However, Shavelle and co-workers107 showed that in US patients with COPD the reduction in life expectancy was less for those who had never smoked
Future directions
Little research has been done into the interaction of risk factors for COPD. The burden of COPD is increasing, especially in developing countries, because of increased cigarette smoking and passive smoke exposure, and also exposure to non-smoking risk factors. Several questions need to be addressed. What is the true burden of non-smoking COPD in different countries? Does non-smoking COPD have the same prognosis, the same radiographic and physiological features, and manifest with the same
Search strategy and selection criteria
References (108)
- et al.
Chronic bronchitis: the effect of cigarette-smoking
Lancet
(1955) - et al.
Prevalence of COPD in Greece
Chest
(2004) Mild and moderate-to-severe COPD in nonsmokers: distinct demographic profiles
Chest
(2005)- et al.
Respiratory symptoms and obstructive pulmonary disease in a population aged over 70 years
Respir Med
(2005) - et al.
Non-reversible airway obstruction in never smokers: results from the Austrian BOLD study
Respir Med
(2008) - et al.
Smoking, respiratory symptoms, and diseases: a comparative study between northern Sweden and northern Finland: report from the FinEsS study
Chest
(2001) - et al.
Prevalence of airways obstruction in a general population: European Respiratory Society vs American Thoracic Society definition
Chest
(2000) - et al.
Chronic obstructive pulmonary disease in five Latin American cities (the PLATINO study): a prevalence study
Lancet
(2005) - et al.
Prevalence of COPD in five Colombian cities situated at low, medium, and high altitude (PREPOCOL study)
Chest
(2008) - et al.
Prevalence of COPD: first epidemiological study of a large region in Turkey
Eur J Intern Med
(2008)
Airway obstruction in relation to symptoms in chronic respiratory disease—a nationally representative population study
Respir Med
Risk factors for chronic obstructive lung disease in Saudi Arabia
Respir Med
Woodsmoke exposure and risk for obstructive airways disease among women
Chest
Chronic bronchitis in women using solid biomass fuel in rural Peshawar, Pakistan
Chest
Obstructive airway diseases in women exposed to biomass smoke
Environ Res
A case-control study on the effect of exposure to different substances on the development of COPD
Ann Epidemiol
Indoor air pollution from biomass fuel smoke is a major health concern in the developing world
Trans R Soc Trop Med Hyg
Chronic obstructive airways disease following treated pulmonary tuberculosis
Respir Med
Tissue remodeling as a feature of persistent asthma
J Allergy Clin Immunol
Asthma as a risk factor for COPD in a longitudinal study
Chest
Effects of early intervention with inhaled budesonide on lung function in newly diagnosed asthma
Chest
The urban factor in chronic bronchitis
Lancet
Smoking, air pollution, and bronchitis in Britain
Lancet
Role of tobacco smoking in the causation of chronic respiratory disease
N Engl J Med
The natural history of chronic airflow obstruction
BMJ
The natural history of chronic airflow obstruction revisited: an analysis of the Framingham offspring cohort
Am J Respir Crit Care Med
Recommandations pour la prise en charge des bronchopneumopathies chroniques obstructive
Rev Mal Respir
The influence of environmental factors in chronic bronchitis
J Occup Med
Air pollution and other local factors in respiratory disease
Br J Prev Soc Med
Role of environment in the development of chronic bronchitis
Eur J Respir Dis Suppl
Chronic obstructive pulmonary disease in lifelong nonsmokers: results from NHANES
Am J Public Health
Chronic bronchitis in non-smokers-does it exist?
Eur J Respir Dis Suppl
Clinical, radiologic, and induced sputum features of chronic obstructive pulmonary disease in nonsmokers: a descriptive study
Am J Respir Crit Care Med
Geographic variations in prevalence and under-diagnosis of COPD: results of the IBERPOC multicentre epidemiological study
Chest
Prevalence, diagnosis and relation to tobacco dependence of chronic obstructive pulmonary disease in a nationally representative population sample
Thorax
European Community Respiratory Health Survey Study Group. An international survey of chronic obstructive pulmonary disease in young adults according to GOLD stages
Thorax
COPD prevalence in a random population survey: a matter of definition
Eur Respir J
Biomass fuels are the probable risk factor for chronic obstructive pulmonary disease in rural south China
Thorax
COPD in Chinese nonsmokers
Eur Respir J
Predictors of chronic bronchitis in South African adults
Int J Tuberc Lung Dis
COPD prevalence in 12 Asia-Pacific countries and regions: projections based on the COPD prevalence estimation model
Respirology
Prevalence of chronic obstructive pulmonary disease in Korea: a population-based spirometry survey
Am J Respir Crit Care Med
Prevalence of chronic obstructive pulmonary disease according to BTS, ERS, GOLD and ATS criteria in relation to doctor's diagnosis, symptoms, age, gender, and smoking habits
Respiration
COPD in Japan: the Nippon COPD epidemiology study
Respirology
Variations in the prevalence across countries of chronic bronchitis and smoking habits in young adults
Eur Respir J
Global burden of disease and risk factors
Children's environmental health. Part two: global environmental issues. Indoor smoke: breaking down respiratory defences
What makes people cook with improved biomass stoves? A comparative international review of stove programs
The health impacts of exposure to indoor air pollution from solid fuels in developing countries: knowledge, gaps, and data needs
Environ Health Perspect
Cited by (1021)
Ageing and disease risk factors: A new paleoepidemiological methodology for understanding disease in the past
2024, International Journal of PaleopathologyEffective-components combination alleviates PM2.5-induced inflammation by evoking macrophage autophagy in COPD
2024, Journal of EthnopharmacologyParticulate matter-induced metabolic recoding of epigenetics in macrophages drives pathogenesis of chronic obstructive pulmonary disease
2024, Journal of Hazardous MaterialsCD146 deficiency aggravates chronic obstructive pulmonary disease via the increased production of S100A9 and MMP-9 in macrophages
2024, International Immunopharmacology