Traditionally, tobacco smoke has been considered the classic trigger for chronic obstructive pulmonary disease (COPD). But about half of all COPD cases worldwide are due to non-tobacco-related risk factors. An Australian research group has studied those risk factors that can also lead to the disease in nonsmokers and kidney smokers.
Over the past decade, the image of the COPD smoker has changed and research into factors in kidney smokers has become more important, write researchers led by Professor Ian Yang, The University of Queensland Thoracic Research Centre, Brisbane [1]. These factors include air pollution, occupational exposures, poorly controlled asthma, environmental tobacco smoke, infectious diseases, and low socioeconomic status. For example, smoking is responsible for about 75% of all COPD cases in Western industrialized countries, but only about 30% in poorer developing countries. Impaired lung growth in childhood, which can be caused by a number of exposures early in life (secondhand smoke, malnutrition, early childhood asthma), is also associated with increased risk of COPD.
Asthma increases COPD risk 12-fold, TB up to 5.8-fold
Potential mechanisms for the pathogenesis of COPD in kidney smokers include inflammation, oxidative stress, airway remodeling, and accelerated lung aging. Compared with smokers who develop COPD, kidney smokers with COPD have relatively mild chronic respiratory symptoms, little or no emphysema, and fewer comorbidities; however, exacerbations may also be common among them, and the risk of lung cancer is greatly increased. Sometimes a single risk factor can be responsible for the development and progression of COPD, but often several coincide. However, if the risk factors are known, practitioners can draw causal conclusions and work with patients to take preventive action.
Those who are asthmatic also have an increased risk of developing COPD – compared to non-asthmatics by a factor of 12. Conversely, one in four COPD patients states that they have already had asthma symptoms in the past. Low educational level, passive smoking, and female gender are risk factors for the co-occurrence of both diseases. Those who have already been hospitalized for respiratory illness as a child also carry a higher likelihood. According to the authors, there are few preventive options – early diagnosis and adequate therapy appear to be most effective.
Those with histological evidence of tuberculosis (TB) have up to a 5.8-fold increased risk of also developing COPD. Yang and colleagues cite changes in lung tissue triggered by the infection as a likely reason. COPD patients with a history of TB tend to be much younger than those in whom the disease can be attributed to smoking. The scientists also point out that HIV infection also significantly increases the risk of COPD.
Eyes open when choosing a career!
In addition to other diseases, the social environment and living conditions can increase the risk of COPD. Painters and varnishers, miners, and other occupations that increase exposure to certain fumes, dusts, and smoke contribute to an increased likelihood of COPD. Another factor is air pollution, which accounts for about 50% of COPD worldwide, the authors write. People in countries with low and medium per capita incomes are particularly affected. In industrially underdeveloped countries, open fires and the prevalence of indoor secondhand smoke are also considered potential triggers. If a person has been abroad for a longer period of time and has possibly adapted to local customs, a targeted query in the medical history can track down a COPD trigger (Box). Also to be considered are level of education and income: Those with lower education and less income are at greatly increased risk of developing COPD. Reasons cited for this include passive smoking at home and at work and a generally reduced awareness of health issues.
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To COPD smoked In the tropics, incense spirals containing pyrethrum are traditionally processed from coconut shells. As a popular and natural mosquito and mosquito repellent, the spirals are first lit and can then glow for up to seven hours – emitting smoke. When the windows are closed, Prof. Yang and his colleagues write, a concentration of fine dust is produced in the closed room that is comparable to 100 burned cigarettes. |
Further research – including epidemiologic, translational, clinical, and implementation studies that explicitly exclude smokers – is needed to fill gaps in understanding and develop potential solutions to reduce the burden of disease in never-smoking COPDers, the authors conclude.
Literature:
- Yang IA, Jenkins CR, Salvi SS: Chronic obstructive pulmonary disease in never-smokers: risk factors, pathogenesis, and implications for prevention and treatment. Lancet Respir Med 2022; 10: 497-511; doi: 10.1016/S2213-2600(21)00506-3.
InFo PNEUMOLOGY & ALLERGOLOGY 2022; 4(3): 26.
