Understanding COPD: For you and your patients

When we published our recent post on Hacking QOF and the essential elements of a COPD review, we promised to follow this up with further material on understanding COPD as a basis for effective reviews. In this post we focus on the basics by looking at what is meant by the term COPD, or Chronic Obstructive Pulmonary Disease.

Defining COPD

Page 67 of the 2024/25 QOF Guidance gives a quick overview of COPD as follows:

Chronic obstructive pulmonary disease (COPD) describes a group of lung conditions that cause obstructive airways disease and includes chronic bronchitis and emphysema.

QOF Guidance 2024/25

This seems a bit restricted and we need to look a bit wider for a fuller definition. We start off with an explanation tailored towards health professionals; then conclude with a simplified animation that we think you’ll love and are sure to want to share with your COPD patients.

A paper in the European Respiratory Journal in 2019 defined COPD as follows:

Chronic obstructive pulmonary disease (COPD) is a common and treatable disease characterised by progressive airflow limitation and tissue destruction. It is associated with structural lung changes due to chronic inflammation from prolonged exposure to noxious particles or gases, most commonly cigarette smoke. Chronic inflammation causes airway narrowing and decreased lung recoil. The disease often presents with symptoms of cough, dyspnoea, and sputum production. Symptoms can range from being asymptomatic to respiratory failure.

Singh et al, Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Lung Disease: the GOLD science committee report 2019,” Eur Respir J, vol. 55, no. 5, May 2019. 

Chest X-Ray from a COPD Patient.

Image Source: Chestatlas.com

This definition defines the symptoms and outcomes that we see in COPD patients, but does not go into the pathophysiological details. We discuss these next.

Emphysema

Emphysema is a COPD-phenotype characterized by destruction of lung parenchyma i.e. destruction of the alveolar air sacs (gas-exchanging surfaces of the lungs) leading to obstructive physiology. Alpha-1 antitrypsin deficiency (AATD) is a genetic cause of emphysema, whereas smoking is the most important risk factor of non-AATD emphysema.

In non-AATD emphysema, an irritant (e.g., smoking, dust, chemicals, pollutants) causes an inflammatory response. Neutrophils and macrophages are recruited and release multiple inflammatory mediators, oxidants and excess proteases leading to the destruction of the air sacs. The protease-mediated destruction of elastin leads to a loss of elastic recoil and results in airway collapse during exhalation.

AATD is a rare cause of emphysema which involves a lack of antiproteases and the imbalance leaves the lung parenchyma at risk for protease-mediated damage. AATD is caused by misfolding of the mutated protein which can accumulate in the liver. AATD should be suspected in COPD patients who present with liver damage. As opposed to smoking-related emphysema, AATD primarily involves the lower lobes.

Chronic Bronchitis and Obstructive Bronchiolitis

Obstructive bronchiolitis is a condition in which chronic inflammation and swelling causes a narrowing of the lumen of the bronchioles, thus interfering with expiration.

Chronic Bronchitis (CB) is defined by the presence of cough with expectorated sputum on a regular basis over a defined period. The classic description defines CB as chronic cough and sputum production for at least 3 months per year for two consecutive years, in the absence of other conditions that can explain these symptoms.

Other causes of COPD

Alongside the causes mentioned above, poor lung development in infancy, family history of respiratory diseases, early life events such as hospitalisations before the age of five years, poor lung development in infancy, gastrointestinal reflux, biomass or chemical fuels used in domestic heating or cooking, severe childhood respiratory infections, chronic bronchial infection, particularly with Pseudomonas aeruginosa, and tuberculosis have all been associated with increased risk of developing COPD.

Patient-friendly Explanatory Video

We thought that the following animation from the Animated Patient series did an excellent job of explaining COPD. Please use it judiciously in your consultations in helping attain the objective of understanding COPD among your patients. Visual learners will especially appreciate it.

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References

If you wish to explore the references we used for this overview, here are the details.