Classification of COPD: fostering prevention and precision medicine in the Lancet Commission on COPD

Chronic obstructive pulmonary disease (COPD) is a highly prevalent and heterogeneous chronic disease of the lower airways and lungs that is associated with huge morbidity, disability, and mortality worldwide and disproportionately affects poor and vulnerable people. 1 Safiri S Carson-Chahhoud K Noori M et al. Burden of chronic obstructive pulmonary disease and its attributable risk factors in 204 countries and territories, 1990–2019: results from the global burden of disease study 2019. BMJ. 2022; 378: e069679 PubMed Google Scholar Pathologically, COPD is characterised by variable degrees of chronic inflammation and remodelling of small airways (bronchiolitis) and destruction of alveolar walls (emphysema). 2 Brusselle GG Joos GF Bracke KR New insights into the immunology of chronic obstructive pulmonary disease. Lancet. 2011; 378: 1015-1026 Summary Full Text Full Text PDF PubMed Scopus (544) Google Scholar Diagnosis of COPD relies on respiratory symptoms and the presence of spirometric airflow limitation. 3 Global Initiative for Chronic Obstructive Lung DiseaseGlobal strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. https://goldcopd.org/2022-gold-reports-2/Date: 2022 Date accessed: July 30, 2022 Google Scholar COPD has long been considered a self-inflicted disease that occurs in adult cigarette smokers as a result of accelerated decline in lung function. 4 Fletcher C Peto R The natural history of chronic airflow obstruction. BMJ. 1977; 1: 1645-1648 Crossref PubMed Scopus (1836) Google Scholar However, epidemiological evidence has shown that many other factors, including indoor and outdoor air pollution, occupational exposures, and use of e-cigarettes and cannabis, also cause COPD. Furthermore, in addition to accelerated lung function decline in adulthood, several other lung function trajectories—characterised by impaired lung development in utero or impaired lung growth in early life—have been linked to COPD. 5 Lange P Celli B Agustí A et al. Lung-function trajectories leading to chronic obstructive pulmonary disease. N Engl J Med. 2015; 373: 111-122 Crossref PubMed Scopus (414) Google Scholar Indeed, COPD can be elicited by early-life events such as prematurity, childhood asthma, and childhood respiratory infections. Importantly, tuberculosis and HIV—common chronic infections, especially in low-income and middle-income countries—can lead to airway obstruction and COPD. Finally, although COPD is a complex disease caused by multiple gene–environment interactions throughout the life course, it is mainly genetically determined in specific subgroups of patients with early-onset COPD or a positive family history (eg, people with α1 antitrypsin deficiency). Towards the elimination of chronic obstructive pulmonary disease: a Lancet CommissionDespite substantial progress in reducing the global impact of many non-communicable diseases, including heart disease and cancer, morbidity and mortality due to chronic respiratory disease continues to increase. This increase is driven primarily by the growing burden of chronic obstructive pulmonary disease (COPD), and has occurred despite the identification of cigarette smoking as the major risk factor for the disease more than 50 years ago. Many factors have contributed to what must now be considered a public health emergency: failure to limit the sale and consumption of tobacco products, unchecked exposure to environmental pollutants across the life course, and the ageing of the global population (partly as a result of improved outcomes for other conditions). Full-Text PDF