COPD is a type of preventable and treatable progressive lung disease that is characterised by long-term respiratory symptoms and airflow limitation. Its main symptoms include shortness of breath and a cough, and possible chronic sputum production. It’s a progressive disease that worsens over time, making everyday activities such as walking or dressing more and more difficult.

COPD continues to be a major public health problem because of its high prevalence, raising incidence, considerable mortality, and associated social and economic costs.

COPD has been traditionally considered a self-inflicted disease caused by tobacco smoking and characterised by an accelerated rate of lung function decline with age. However, about a third of patients with COPD are never smokers and about half of patients with COPD develop the disease without evidence of any acceleration of the physiological rate of loss of lung function, clearly indicating that there must be other pathogenic mechanisms to consider. In fact, a large general population study in Austria has identified many environmental factors (including but going beyond smoking) associated with reduced lung function in different age bins throughout life.

COPD can no longer be considered a “uniform” disease, so the traditional definition and classification of COPD needs to be revisited and updated (including that of the episodes of exacerbations of the disease). A recent paper proposes that “COPD is a heterogeneous lung condition characterised by chronic respiratory symptoms (dyspnea, cough, expectoration) due to persistent abnormalities of the airways (bronchitis, bronchiolitis), and/or alveoli (emphysema) that cause persistent, often progressive, airflow limitation”. It also recognises that there are different “types” of COPD according to the cause, including genetic COPD, COPD due to abnormal lung development, environmental COPD (which includes cigarette smoking), COPD and biomass and pollution exposure, COPD due to infections, COPD and asthma, COPD of unknown cause, and COPD of mixed causes. So far, research has focused almost exclusively on COPD-cigarette smoking. It is necessary to consider these different forms of COPD to investigate their natural history and optimal treatment. In this setting, a management strategy based on so-called treatable traits (TTs) seems advisable. This is a precision medicine strategy, which is agnostic (i.e. independent) of the traditional clinical diagnosis (COPD, asthma, and asthma-COPD overlap) and based on the identification of TTs in each individual patient. TTs can be identified based on “phenotypic” (i.e., clinical) recognition and/or on a deep understanding of critical causal pathways (“endotypes”) through validated “biomarkers”.

Finally, it is now accepted that COPD can occur in young subjects (<50 yr of age) and that some individuals may have (at any age) structural (e.g. emphysema) and/or functional lung abnormalities (e.g., low carbon monoxide diffusing capacity) in the absence of airflow limitation (Pre-COPD) that may progress to COPD or not.

Based on article: Am J Physiol Lung Cell Mol Physiol323: L615–L618, 2022

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