COPD primarily affects adults over 45 years of age, and rates as one of the major causes of death world-wide. The World Health Organisation rates COPD as the fourth most common cause of death throughout the world. An alarming rise in the prevalence of this condition, particularly among women, indicates that mortality and morbidity (illness) due to COPD may be much higher by 2020.
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Patients with this condition experience a prolonged decline of exercise capacity and in the final years of their life are severely dyspnoeic (short of breath), often unable to lead a normal life and needing to be maintained on continuous medical support systems and therapy. This incurs great personal and national expense, which in the USA amounted to a total cost of $23.9 billion in 1993. (By comparison, the total bill for asthma was $12.6 billion and pneumonia $7.8 billion.) The financial burden of COPD, particularly in developing countries, will parallel the ongoing abuse of factors that cause the disease, such as smoking.
Reversing this trend will take time: the effects of successful public education programmes will only be noticed in several decades, given that the negative effects of smoking become apparent 30-40 years after its onset.
Risk Factors
Host factors
Genes (e.g. alpha-1 antitrypsin deficiency)
Airway Hyper-responsiveness
Lung growth
Exposure
Tobacco smoke
Occupational dusts and chemicals
Indoor and outdoor air pollution
Infections
Socio-economic status
The role of tobacco smoke as a causative agent for COPD has been proven beyond all doubt. It appears that starting smoking at a young age, the "total pack years" (the number of cigarettes smoked per year multiplied by the number of years of smoking) and the person's current smoking status all contribute to the final state of respiratory impairment due to COPD. In spite of this, only an estimated 20% of smokers develop the disease. However, this figure does not take into consideration the combined effect of several other risk factors that commonly occur in individuals in underprivileged communities, with a subsequent greater likelihood of developing the disease.
Evidence has been found that secondary cigarette smoke can cause COPD in non-smoking bystanders. This has serious health and legal implications, as smokers could jeopardise the health of the non-smoking population.
In a number of occupations, including mining and industry, dust and exposure to welding gases and fumes have been associated with the development of COPD. Enforcement of protective measures in the workplace, including wearing masks and monitoring levels of dust and toxic fumes, have minimised and in some cases abolished the danger of industrial exposure.
Low socio-economic status is a risk factor for the development of COPD due to the high prevalence of other risk factors, including secondary cigarette smoke exposure, particularly in childhood; and tuberculosis, which tends to occur in deprived communities. Good evidence has been found that tuberculosis (TB), particularly recurrent episodes of the disease, leads to the development of COPD in up to 30% of patients in developing countries. Additional risk factors in disadvantaged communities include the indoor burning of biomass fuels and a tendency to recurrent chest infections, which in their own right cause further damage to the bronchial walls and contribute to the onset of COPD. In these communities, children of parents who smoke are at a proven disadvantage, as recurrent chest infections and impaired lung growth predispose these unfortunate individuals to early development of COPD.
The fact that many industrial workers and miners smoke and contract tuberculosis serves as one example of how combinations of risk factors contribute through a final common pathway of airway inflammation to create an accumulative burden for causing COPD.
It should be evident that as long as these risk factors prevail in communities, the disease prevalence will continue its upward spiral and continue to be a major burden on national and personal health budgets.
Asthmatics and COPD
Young asthmatics who smoke or who are exposed to noxious agents in the workplace tend to have an early onset of COPD. A common mistake, however, is to label wheezy COPD patients as asthmatics. Asthma is a disease that tends to have its onset in the teens or early adulthood, is usually associated with hay fever and is caused by readily definable antigens that induce attacks of airway obstruction. (For the sake of specific treatment, the attending physician has to make a decision of where asthma ends and COPD starts). Treatment and prognosis for asthma is completely different to that for COPD, with a favourable response to treatment in asthmatics and less so in COPD patients.
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