Chronic obstructive pulmonary disease (COPD) and asthma are highly prevalent, non-malignant respiratory conditions that have increased dramatically in the past half century, both in high-income and low-middle-income countries. COPD is the fourth leading cause of death worldwide, and both COPD and asthma have a profound impact on quality of life for patients and their families. Tobacco smoke remains the single most important cause of COPD, but occupational and indoor exposures have increasingly been recognized as risk factors, especially among middle- and low-income individuals. Different patterns of genetic susceptibility independent of exposure result in variability of disease expression with many patients not developing clinical COPD, although they may still develop respiratory symptoms. COPD prevalence differs greatly between countries even when controlling for smoking rates. While much progress has been made in understanding biological pathways involved in asthma, the understanding of why asthma initially develops remains elusive. Although a large number of potential risk factors have been identified, none can explain the global increases in asthma prevalence observed over the last few decades. Prevalence trends between countries have also varied, with some countries continuing to experience increases in asthma rates and some rates levelling off or even declining. These trends cannot be explained by divergent epidemiological methods or population makeup alone. Asthma control, especially for severe asthmatics and for those with non-allergic phenotypes, remains a public health problem with more efficient interventions needed to encourage smoking cessation, improve air quality, and reduce allergen exposure.
Risk factors of chronic obstructive pulmonary disease among adults in Chinese mainland: A systematic review and meta-analysis
