COPD Definition, Facts, Alarming Statistics and Pathophysiology

What is COPD

COPD, the medical abbreviation for Chronic Obstructive Pulmonary Disease, is a long-term progressive disease of the lungs where the air that you breathe in is obstructed by the diseased lung pathology causing breathing to become difficult.

The word “progressive” indicates that the disease worsens over time. It is a major cause of disability restricting the normal activities of a person. COPD develops gradually over the years. Therefore you will normally see its symptoms after the age of 35 to 40 years though it has developed earlier.

The lung’s structure undergoes physical changes causing damage to its normal parenchyma and this pathophysiology can be described as the basic etiology of COPD.

The main cause is smoking while environmental pollution and genetic factors also contribute.

COPD awareness

The global awareness of COPD among the population is very poor especially among the people of the developing countries.

According to a study conducted in 2001, the awareness in Brazil was 4% (the lowest), while in Germany, it was 10% (the highest).

As years passed, the awareness increased. Today most Americans (about 40%) are aware of this condition but more than half of those 24 million affected remain undiagnosed.

The COPD Foundation is a non – profit organization founded on June 14, 2004, and headquartered in Miami, Florida.

“Its mission is to prevent and cure Chronic Obstructive Pulmonary Disease and to improve the lives of all people affected by COPD.” It has worked hard to create awareness about COPD and over the decade has shown good results”.

The World Health Organization (WHO) is another body, which works towards raising awareness of the global epidemics of non-communicable diseases such as COPD.

It works towards encouraging healthy lifestyle habits and discouraging the use of tobacco among the population.

COPD definition

The current medical definition of COPD as provided by the American Thoracic and European Respiratory Societies and quoted in is:

“COPD is a preventable and treatable disease state characterized by airflow limitation that is not fully reversible. The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lungs to noxious particles or gases, primarily caused by cigarette smoking. Although COPD affects the lungs, it also produces significant systemic changes.”

COPD is not contagious, meaning it does not pass from one person to another. Chronic bronchitis and emphysema are the two most common diseases of the lungs that make up this condition and most people with COPD have both emphysema and chronic bronchitis.


To understand the path physiology of COPD, it will help to understand briefly the normal parenchyma of the lungs.

Normal lung physiology

The air that we breathe in travels through the windpipe (called Trachea), which branches into the left and the right airway (bronchus) for the corresponding lung.

Each bronchus then branches out into smaller bronchi and then thousand of bronchioles, which reach out into every part of the lungs.

These small and tiny bronchioles have thin-walled air sacs called alveoli at their ends. There are small blood capillaries running through the walls of these alveoli.

It is in the alveoli that exchange of gases take place. The inhaled oxygen fills up the alveolar sacs.

The blood capillaries have brought in the blood, which is carrying carbon dioxide and other waste gases from the body.

Oxygen is passed from the air sacs (alveoli) into the blood in the capillaries and carbon dioxide is passed through the blood to the air sacs to be exhaled. This exchange of gases is called gas exchange.

The airways and the alveoli are elastic in nature. They inflate with air when you breathe in. When you breathe out, they deflate. This elastic property of the airways and the air sacs is important for normal breathing.

COPD pathophysiology

According to the COPD foundation,

“Chronic Obstructive Pulmonary Disease (COPD) is an umbrella term used to describe progressive lung diseases including emphysema, chronic bronchitis, refractory (non-reversible) asthma, and some forms of bronchiectasis.”

But, usually, it is a combination of two main lung conditions namely chronic bronchitis and emphysema. Both these conditions cause difficulty in breathing.

So, you have a double whammy with COPD giving you the symptoms of both these lung conditions. To make it worse, as explained above, the disease is progressive and the complications and the prognosis don’t look so good.

With COPD, the physical changes that take place in the lung parenchyma describe its pathophysiology.

These pathological changes interfere with the normal breathing and less air flows into the lungs because of obstruction to the airflow through the bronchi.

Any of the following can cause the disturbance in the normal breathing pattern:

  • The walls of the alveoli  become thick and inflamed.
  • The walls of the alveoli (air sacs) are damaged.
  • Due to inflammation of the walls of the bronchi, too much mucus is secreted, which blocks them.
  • The elastic property of the bronchi and the alveoli is lost.

There is no cure for this disease. Treatment only prevents further damage and controls the symptoms.

Facts about COPD statistics in the U.S., the U.K. and worldwide

COPD has now become a global epidemic. The facts described below show an alarming increase in its incidence and prevalence.

Statistics show that COPD is the third largest cause of death in the developed countries, after heart disease and cancer. It has overtaken stroke, which used to rank third.

According to WHO statistics, which are available for 2012, about 64 million people have this condition worldwide. About 3 million people died from this disease that year, which is equal to 6% of all deaths globally from various causes that year.

90% of the deaths occurring every year are from the low-income group countries.

In the United States, more than 6% of the population suffers from this lung disease – that is roughly about 24 million people.

About 120,000 people die of COPD every year in the United States. Increased cigarette smoking habit is the main reason for this voluminous increase.

Another significant observation is that in the United States more women now die of COPD than men

In the United Kingdom, it has overtaken breast cancer as the commonest cause of death in women. About 10% of men and women in the UK have this Chronic Obstructive Pulmonary Disease.

That is, about 3 million people in the UK are estimated to have COPD of which only 1 million have been diagnosed.

Formerly, the prevalence of COPD was more in men but now it affects both men and women equally. The reason could be due to an increased number of women taking up smoking, especially in the developed countries.

Healthcare costs incurred are three times more that those for asthma. It also rates as one of the most common causes of hospital admissions in the developed countries.

COPD mortality rate     

As stated above, COPD ranks third as the leading cause of death after heart disease and cancer.

The 5-year mortality rate for people with COPD varies from 40% to 70%, while the 2-year mortality rate for people with severe COPD is about 50%.

The mortality rates of severe cases are, in fact, worse than many common cancers.

Another significant but disturbing fact is that the mortality rates for heart diseases and cancer have fallen significantly by 59% to 64% over the last 30 years, while those of COPD have doubled.

The main cause of these alarming statistics is an increase in the smoking habit among the population and women in particular.

The COPD Foundation has an informative map showing the prevalence of COPD in the various states of the United States.