chronic obstructive pulmonary disease

Last edited 07/2022 and last reviewed 11/2023

Chronic obstructive pulmonary disease (COPD) is a condition characterised by airflow obstruction, which is usually progressive, not fully reversible and does not change markedly over several months (1).

Although the American Thoracic Society (ATS), British Thoracic Society (BTS), and European Respiratory Society (ERS) definitions of COPD emphasize chronic bronchitis and emphysema, the Global Initiative for Chronic Obstructive Lung Disease (GOLD), in its 2017 report, has revised the definition to include airflow limitation (not airflow obstruction) and its association with abnormal inflammatory response of the lungs to various noxious particles or gases. GOLD defines COPD as: (2)

“a common, preventable a treatable disease that is characterised by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities usually caused by significant exposure to noxious particles or gases” (2).

Chronic airflow limitations present in COPD is caused by a combination of small airway disease (e.g. obstructive bronchiolitis) and parenchymal damage (emphysema).  

• relative contributions of these two changes varies from person to person and do not always occur together, but evolve at different rates over time (2)
• chronic inflammation of the airways result in structural changes, narrowing of small airways and destruction of the lung parenchyma.
• these changes lead to loss of alveolar attachments to the small airways and decreases lung elastic recoil which in turn diminish the ability of the airways to remain open during expiration
• loss of small airways may also contribute to airflow limitation and mucociliary dysfunction is a characteristic feature of the disease (2) 

COPD is an important cause of activity limitation in the population.

• approximately 1.2 million people have a diagnosis of chronic obstructive pulmonary disease (COPD) in the UK (1)
  • although there are 115,000 new diagnoses per year, most people with COPD are not diagnosed until they are in their fifties or older and many more people may remain undiagnosed
  • UK has the 12th highest recorded deaths from COPD in the world, with an age standardised mortality rate of 210.7 deaths per million people between 2001 and 2010

Reference:

• (1) National Institute for Health and Clinical Excellence (NICE) 2018. Chronic obstructive pulmonary disease: Management of chronic obstructive pulmonary disease in adults in primary and secondary care.
• (2)Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2021. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease