COPD – son of a TB
By Andre F.S. Amaral, Research Associate, National Heart and Lung Institute
Chronic obstructive pulmonary disease (COPD) is characterised by chronic airflow obstruction and is the third most common cause of death worldwide, especially in low and middle income countries (LMICs). The main risk factor for this disease is tobacco smoking. However, smoking is still uncommon in many LMICs and more than 20% of people with COPD do not have a history of smoking.
What could then be causing COPD among people who do not smoke?
Some have advocated that the high number of deaths by COPD among non-smokers, especially in LMICs, could easily be explained by a high exposure to smoke from burning biomass for cooking, heating and lighting. However, large studies have ailed to find an association of airflow obstruction with use of biomass.
Others have suggested that infectious diseases, which are still common in LMICs, could have a role in COPD. Pulmonary tuberculosis (TB) is the leading cause of mortality due to respiratory infection worldwide, but with its death rate decreasing since 1990 several millions of people are saved every year. Broadly speaking there is considerable overlap between regions with high incidence of TB and high mortality from COPD, therefore it makes sense to improve our understanding of the relationship between these two diseases.