Chronic obstructive pulmonary disease (COPD) is a condition that occurs when the flow of air into the lungs is obstructed. It is caused by exposure to pollutants, in particular from smoking tobacco, which activates a particular inflammatory response in the lungs.
While there is no cure, early diagnosis and treatment can make a significant difference to quality of life and activity.
Classification of COPD
COPD is classified by a narrowing of the airways limiting airflow to the lungs, which causes increasing breathlessness over time.
A progressive disease that cannot be reversed, COPD is characterised by “acute exacerbations”, when a person’s symptoms suddenly become worse.
COPD is usually diagnosed with a spirometry test, which measurs how much air is exhaled after the patient inhales the maximum intake of breath. Spirometry testing can detect whether there is any obstruction to airflow, where it is situated and how it can be treated.
The three guidelines most often used to assess lung damage are from the National Institute for Health and Clinical Excellence (NICE), the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the American Thoracic Society/European Respiratory Society (ATS/ERS).
What causes COPD?
The most common cause is smoking tobacco, however COPD can also be caused by being exposed to second-hand smoke or from living or working in an environment where you are exposed to pollutants.
Is COPD the same as emphysema and other lung conditions?
The lung conditions of emphysema and chronic bronchitis are generally considered to fall under the umbrella term of COPD.
Emphysema is when the alveoli (air sacs) in the lungs are damaged and inflamed. When someone with emphysema breaths, there is less surface area available for oxygen and carbon dioxide to be exchanged. Their lungs will also suffer a reduction in elasticity, which can cause collapsed airways and limited airflow.
Chronic bronchitis is defined by lung damage and inflammation in the airways. It causes an increase in the number and size of the goblet cells and mucus glands, resulting in an increase in the production of mucous, which is then coughed up as sputum.
Prevalence of COPD
COPD is frequently underdiagnosed because of the need to measure accurately the obstruction of airflow, which means that most data tends to come from first-world countries. It is also not usually diagnosed until it is already causing at least moderate symptoms.
There is also a large variation in the number of cases in different parts of the world, depending on how well a country gathers data on COPD, how common smoking is there and the average age of the population, as the disease is more prevalent as people age, especially among those who smoke.
However, cases are believed to be on the rise. A 2006 study showed prevalence of the disease worldwide to be 210 million people, and by 2030 COPD is expected to be the fourth leading cause of death.
A 2000 study indicated that there are around three million people with COPD in the UK and a 2006 study suggested that it accounts for 23% of respiratory deaths, with women more likely to develop the disease than men.