Chronic obstructive pulmonary disease, or COPD, is an umbrella term for lung conditions that block airflow and make breathing difficult.
Nearly 15.7 million Americans report having been diagnosed with COPD, according to the Centers for Disease Control and Prevention (CDC). But the number may be much higher, because more than half of all adults with low pulmonary function have COPD without knowing it. (1)
Chronic lower respiratory disease — of which COPD is the biggest component — is the third leading cause of death in the United States, according to data from the National Center for Health Statistics. (2)
The number of U.S. deaths from chronic lower respiratory diseases totaled 155,041 in 2015, according to the latest CDC data. (3)
Certain groups of people are more likely to report having COPD. (1) Among these groups are:
"Think of COPD as a spectrum of disease, with chronic bronchitis on one end and emphysema on the other," says Jeffrey Michaelson, MD, a pulmonologist with WellStar Medical Group in Marietta, Georgia.
Asthma, a lung disease in which the lungs' bronchial tubes, or airways, become inflamed, is usually recognized as a distinct disease separate from COPD. Still, there is considerable overlap between the diseases, in terms of symptoms, triggers, and diagnostic testing. (5)
“[COPD and asthma] are both lung diseases that affect the airways, and they have similar symptoms, including cough, shortness of breath, wheezing, and chest tightening,” says David A. Beuther, MD, a pulmonologist at National Jewish Health in Denver.
Asthma episodes are usually associated with variable airflow obstruction of the lungs, as opposed to the chronic airflow limitation associated with COPD.
COPD shares many signs and symptoms with asthma, and there is also overlap in treatment. But the conditions are very different.
Asthma is a chronic disease in which the lung’s airways (bronchial tubes) become inflamed and sensitive to environmental triggers, such as dust, smoke, pet dander, or cold air. Most people are diagnosed with asthma in childhood and develop symptoms by age 5. Symptoms of asthma are intermittent, with periods of time when no symptoms exist.
People with COPD, on the other hand, usually don’t get diagnosed until they are 40 or older. Smoking is the main risk factor for developing this progressive disease. Symptoms of COPD are persistent.
People with asthma may eventually develop COPD. A study published in May 2016 in the New England Journal of Medicine found a link between persistent childhood asthma and COPD in early adulthood. Researchers followed nearly 700 participants and found that 11 percent suffered from COPD as young adults.
Emphysema occurs when the air sacs of the lungs (alveoli) become damaged and enlarged, causing breathlessness. Each lung has an average of 480 million alveoli. (6)
When you breathe in, the alveoli expand and stretch, taking in oxygen and transporting it to the blood in the small capillary vessels within their thin walls. When you breathe out, the alveoli easily deflate, expelling carbon dioxide out of the body through the airways.
In people with emphysema, the alveolar walls become damaged and the air sacs lose their normal elasticity, causing the airways to the lungs (bronchioles) to collapse.
“Symptoms of emphysema deal with progressive shortness of breath that limits activity,” says Dr. Michaelson. Other common symptoms include chronic cough, frequent respiratory infections, wheezing, reduced appetite, and fatigue.
Cigarette smoking is the leading cause of emphysema. Other risk factors for the disease include frequent childhood respiratory infections, asthma, and chronic exposure to air pollution, secondhand smoke, or workplace dust and smoke.
In rare cases, it can be caused by the hereditary disorder alpha-1 antitrypsin (A1AT) deficiency. People with this deficiency have low levels of a protein made in the liver, which can lead to lung damage if exposed to airborne irritants.
"There are two main types of COPD: emphysema and chronic bronchitis. Most people with COPD suffer from both."
Bronchitis is an inflammation of the bronchial tubes (airways), which bring air to and from the lungs. When the bronchial tubes are inflamed, the lining, or mucous membrane, of the airways swells and grows thicker. It also produces an excess amount of mucus.
Bronchitis can be either acute or chronic. Acute bronchitis typically results from temporary infections and lung irritants, and is commonly caused by the same viruses that cause colds and the flu. Most cases of acute bronchitis clear up within a few days.
Chronic bronchitis is a far more serious, incurable lung disease involving periods of persistent coughing that signals underlying structural changes to the bronchial system. Aside from the mucus-laden cough, people with chronic bronchitis experience shortness of breath, tightness of the chest, wheezing, and fatigue.
Cigarette smoking is the most common cause of COPD, including chronic bronchitis. Other possible causes of chronic bronchitis include exposure to industrial dust and fumes in the workplace, indoor air pollution, secondhand smoke, and other air pollutants; asthma; and frequent childhood respiratory infections.
Unlike some cases of emphysema, chronic bronchitis is not caused by the genetic disorder alpha-1 antitrypsin (A1AT) deficiency.
All forms of COPD, including emphysema and chronic bronchitis, stem from airborne irritants that are inhaled.
Smoking is the main cause of COPD, though nonsmokers can also get the disease. According to the American Lung Association, between 85 and 90 percent of all COPD cases are caused by cigarette smoking. (7) Still, 1 out of 4 Americans with COPD never smoked cigarettes. (8)
Most people who develop COPD symptoms are at least 40 years old. People younger than 40 years of age can have COPD, too, but it's uncommon.
Other causes of COPD include:
"Smoking is the main cause of COPD, though nonsmokers can also get the disease."
COPD symptoms can develop slowly. There may be no apparent symptoms at first.
In the early stages, symptoms may be mild and include:
As the condition worsens, other symptoms may develop, such as:
In severe cases, COPD may also cause mental confusion and disorientation.
People with COPD often experience exacerbations, or periods of time when symptoms worsen, which usually occurs when environmental air pollution increases.
The Global Initiative for Chronic Obstructive Lung Disease (GOLD) — which was launched in collaboration with the National Heart, Lung, and Blood Institute (NHLBI), the National Institutes of Health (NIH), and the World Health Organization (WHO) — established guidelines to determine the stages of COPD.
The GOLD system breaks down COPD severity into four stages based on a unit of measurement known as forced expiratory volume (FEV1). FEV1 is the maximum amount of air exhaled by the lungs in one second. The lower the FEV1, the lower a person’s lung capacity and the more severe their COPD.
By comparing a patient’s FEV1 with expected values considered to be healthy, a doctor calculates a percentage that determines what stage COPD a person has. (9)
The four COPD stages or grades are:
Another COPD-related measurement is the forced vital capacity (FVC) test, which is the amount of air a person can force out of the lungs after inhaling as much as possible.
The ratio of FEV1 to FVC is used to determine lung capacity — an FEV1/FVC ratio of around 80 percent is considered healthy. All four COPD stages are characterized by an FEV1/FVC ratio of less than 70 percent. (9)
Mild COPD involves minor airflow limitation.
Symptoms may include:
Treatment may include a short-acting bronchodilator and smoking cessation if the patient smokes.
With moderate COPD, airflow limitation begins to worsen.
Symptoms, which are similar to mild COPD, include:
Treatment may include long-acting inhalers and pulmonary rehabilitation.
Severe COPD means that lung function has been seriously impaired, and the condition is having a noticeable impact on the patient’s quality of life.
In addition to chronic coughing, sputum, and dyspnea, severe COPD symptoms include:
The goal of stage 3 COPD treatment is to manage the disease’s symptoms. Treatment options are the same as for stages 1 and 2, and may also include inhaled corticosteroids.
Very severe COPD, also known as end-stage COPD, means that the patient’s breathing difficulties have become life-threatening. The disease starts to affect the heart and circulatory system.
In addition to severe COPD symptoms, signs of end-stage COPD include:
Treatment may require oxygen therapy or surgery.
While symptom flares are a common COPD complication, the disease can lead to many health problems.
Diagnosing COPD usually involves an assessment of the patient’s health history combined with performing certain tests.
To determine whether you have COPD, the doctor will typically begin by asking questions regarding symptoms, smoking habits, exposure to airborne irritants, and family history of COPD or the genetic disorder alpha-1 antitrypsin (A1AT) deficiency, which can cause emphysema.
A physical examination is performed to inspect the strength and function of your lungs and heart, and to look for any visible signs of COPD, such as cyanosis (blueness of the lips and fingernail beds).
Your doctor may order one or more lung function tests, such as:
Your doctor might also order blood tests and imaging scans, such as:
Other diagnostic tests may also be necessary, such as a heart test called electrocardiogram (EKG), bronchoscopy (where a thin tube with a camera is inserted into the airways to examine the lungs), and a lung or bronchial biopsy.
One of the best ways to prevent getting COPD is to never start smoking, or to stop smoking if you already do.
If you have trouble quitting smoking, there are numerous options to help you, including gums, patches, and prescription medication. Additionally, support groups and classes to help you quit smoking can often be found through hospitals, workplaces, and community associations.
Heavy and long-term exposure to various lung irritants, including air pollution, dust and chemical fumes in the workplace, and secondhand smoke, can also cause COPD.
Here are some tips to reduce your exposure to COPD-causing irritants:
There is no cure for COPD. Treatment focuses on relieving symptoms, improving quality of life, and correcting lifestyle habits that may worsen the condition.
To slow the progression of the disease, it's important to stop smoking and avoid exposure to lung irritants.
Pulmonary rehabilitation, which can improve your well-being, may include:
Medication that may be part of a COPD treatment plan may include:
There are many resources available to learn more about COPD, its causes, prevention, and treatment. There are also support groups for people who have been diagnosed with the disease or who are caregivers for people with COPD.
Additional reporting by George Vernadakis.