COPD Risk Factors

COPD Risk Factors
Mohamed M.Elbatamouny
Prof.of.Hospital Medicine
Cairo University
The strength of evidence that smoking is a cause of COPD comes from many studies and has been growing for many years
Cigarette smoking
Personal direct cigarette smoking is the most important single causal factor for developing COPD. In addition,the estimated fraction of COPD mortality attributable to cigarette smoking in the adult population worldwide in 2000 was around 53% for men and around 22% for women.There was more variation between regions of the developing regions than in industrialised regions. In the fourteen epidemiological subregions of the world defined by the WHO the attributable fractions were higher in industrialised countries(around 83% for men and 62% for women) compared with developing countries(around 47% for men and 16% for women) Cigarette smokers have respiratory symptoms and lung function more abnormalities than non-smokers and cumulative smoking exposure may be predictive of COPD mortality.Nonetheless,even though less individuals are concerned, pipe and cigar smoking is also associated with an increase in COPD mortality, although the risk may be lower than for cigarette smoking.The risk associated with smoking is Complex and multifactorial, depending on, inter alia, the age at which smoking began, the duration of smoking, the number of Cigarettes smoked per day, nicotine content, cigarette and filter type, and environmental and, behavioural factors.
In addition, these factors may be influenced by the socioeconomic context In the Middle East and Africa, smoking rates are generally high and rising. Cigarette smoking is traditionally a pursuit of men. but recent years have seen more and more women take up cigarettes, particularly in more Westernised societies such as Lebanon and Turkey.
In the last years, waterpipe smoking, which is originally from India, has gained popularity especially in the Middle East region, North America and Europe. This reflects dramatic changes in patterns of tobacco use in young people worldwide. A survey involving data from 16 countries in the Middle East region suggests that waterpipe smoking rates range from 6 to 34% among 13- to 15-year old Outside the Middle East, two studies performed among French and British students found that around 40% of male students had experimented with other tobacco products including the waterpipe. Several factors have contributed to the increased rate of waterpipe such as targeted marketing, use of sweet additives to attract use by women, young girls and boys. Also, the waterpipe is used as a substitute for cigarette smoking and is considered as a form of social smoking because pipes are shared among friends and family Among Arab women, waterpipe smoking carries less of a cultural stigma than does cigarette smoking. In the BREATHE study rates ofwaterpipe use in, an older population of subjects aged at least forty were 5.8% in men and 1.4% in women. Large disparities between countries were however noted, waterpipe use being highest in the countries of the Near East and Saudi Arabia and lowest in the Maghreb countries.
Nonetheless, like cigarette
smoking, waterpipe smoking increases the risk of lung cancer respiratory illness and low birth weight. It was reported that the level of nicotine absorption produced by daily waterpipe smoking is similar to that produced by daily cigarette smoking. Smokers report features of dependence such as drug-seeking behaviour and inability to quit despite repeated attempts Tobacco smoke generated by waterpipes contains nicotine, carcinogenic substances and heavy metals. Exposure to carbon monoxide(Co), which is one of the major cardiovascular risk factors associated with smoking may be even higher for waterpipes than for cigarette smoking. One study has shown that the level of CO expired by cigarette or waterpipe smokers before and after smoking increased by >100% in cigarette smokers and by >450% in waterpipe smokers. In contrast, nicotine exposure seems to be lower
Waterpipe smoking is also an important source of indoor air pollution, particularly with respect to indoor venues such as cafes, restaurants and waterpipe bars.
A recent study in Pakistan showed that the mean level of particulate matter ≤ 2.5 microns in diameter was 101 μg/m3 for non-smoking venues, 689 μg/m3 for cigarette smoking venues and 1745 μg/m3 for waterpipe smoking venues
Non smoking factors/outdoor and indoor air pollution
Although tobacco smoking is established as the major risk factor for developing COPD other risk factors have been shown to be mportant, several of which are particularly relevant for developing countries. Epidemiological studies have found that the proportion of patients with COPD who have never smoked ranged from 25 to 45% depending on the country Indoor air pollution from biomass fuel has been implicated as a risk factor for the development of COPD. A number of studies hav consistently linked biomass
smoke exposure especially related to cooking on open fire stoves, with the development of chronic bronchitis and spirometrically-defined COPD in women In contrast, the role of outdoor air pollution in causing COPD has not been established unequivocally. However. strong evidence indicates that daily variation in exposure to outdoor air pollution correlates with the occurrence of chronic bronchitis and acute exacerbations of COPD. In addition, a recent study performed in adult former or current smokers in the USA showed that exposure to wood smoke further increases the risk for reduced lung function in cigarette smokers by a factor of around two
Occupational exposure to dusts and chemicals
In addition to cigarette smoke, occupational exposure to airway irritants has been identified as the second most important risk factor for COPD in more developed countries A study performed in the USA regarding the impact of occupational exposure on the development of COPD shows that 20% of COPD cases may be attributable to occupational exposures, and past occupational exposure significantly increased the risk of COPD independently from the effects of smoking Moreover, several community based studies have demonstrated, in addition to the appearance of respiratory symptoms, a more rapid annual decline in FEV associated with occupational exposure to dust, gases and fumes. In 2000, a study

performed among employees of two cement factories in Morocco revealed that pulmonary function was altered significantly in those exposed to cement dust compared to those not so exposed
a1-Antitrypsin deficiency
The relationship between genetic factors in non-smokers and COPD has been less widely studied. However, several lines of evidence suggest that individuals with hereditary a1-antitrypsin deficiency have an elevated risk of developing COPD compared to non-smokers with a normal complement of al-trypsinase activity. Nonetheless
in these subjects, the development of airflow obstruction and respiratory symptoms are variable suggesting that other factors in addition to genotype, including age >50 years, male sex,wheezing and occupational exposure, may contribute to the development of COPD in these individualsm Socioeconomic Status
Lower socioeconomic status
is associated with a higher risk of developing COPD and is likely to be associated with other factors such as growth retardation, poor housing conditions and nutrition,low income, low educational level, and exposure to environmental risk factors.
Lower education and lower monthly income were described to be independently correlated with a risk of acute COPD exacerbation (risk ratio: 1.5 and 2.1 respectively) in the USA In addition, a significant correlation between lung function and socioeconomic status has been suggested.The magnitude of the effect of low socioeconomic status on lung function is variable, but FEV, reductions have been reported). It is difficult to dissociate the role of socioeconomic variables from other COPD risk factors such as smoking or exposure to polluants that vary with socioeconomic status
Comorbidities
COPD itself has extrapulmonary systemic effects that may facilitate the appearance of comorbidities. Data from the Netherlands show that up to 25% of the population with COPD of 65 years and older present two comorbidities and up to 17% present three such conditions. Weight loss, nutritional abnormalities and skeletal muscle dysfunction are well-recognised extrapulmonary effects of Copd. In addition, COPD patients are at increased risk for many other diseases such as myocardial infarction, angina, osteoporosis, respiratory infection, bone fractures, depression, diabetes, and lung cancer Depression is described as a frequent comorbid condition in patients with COPD in a study in England. An average of 45% of older adults with COPD met criteria for depression