End-stage COPD usually involves the need to transport your own oxygen supply.

Once you’ve been told you have chronic obstructive pulmonary disease (COPD), it’s important to find out where you are as far as COPD stages are concerned. COPD stages include mild (Stage 1 COPD), moderate (Stage 2 COPD), severe (Stage 3 COPD), and very severe (Stage 4 COPD).

These classifications are based on increasing severity of airflow restriction and symptoms, and they help doctors determine an individual’s COPD treatment guidelines and life expectancy.

Accessing COPD Stages

A COPD test called spirometry is generally used to determine which of the COPD stages you’re in. A spirometry test involves taking a deep breath in and then exhaling as hard and as long as possible into a hose connected to a machine called a spirometer. The machine measures how fast air is blown out of the lungs, as well as the total amount of air inhaled and exhaled.

The spirometer can be used to take several types of measurements. Some common ones used in the diagnosis and management of obstructive lung diseases are as follows:

• Forced vital capacity (FVC): The total amount of air you can forcibly blow out after inhaling.
• Forced expiratory volume in 1 second (FEV1): The amount of air you can blow out in one second.
• The ratio of FEV1 to FVC (FEV1/FVC): In healthy adults, this should be 75 to 80 percent.
• Peak expiratory flow (PEF): The speed of air moving out of your lungs at the beginning of an exhalation.

COPD Stages: Defining Each Level

Doctors use four COPD stages to gauge patients with the condition.

• COPD Stage 1: Your spirometry test shows mild limitation in airflow (FEV1 greater than 80 percent of predicted for a person of the same age with no lung disease). At this early stage, your COPD signs and symptoms may be barely noticeable. It is likely you are unaware that your lung function is impaired, although you may have a chronic cough, with sputum production.
• COPD Stage 2: Your spirometry test shows limitation in airflow that is worse than in mild COPD (FEV1 less than 80 percent but greater than 50 percent of predicted for a person of the same age with no lung disease). Your COPD signs and symptoms are becoming more obvious—you may notice that you are experiencing shortness of breath when you exert yourself, and a cough and sputum production are more likely than in Stage 1 COPD. Your growing awareness of your breathing problems may lead you to seek medical attention.
• COPD Stage 3: This is severe COPD. Your airflow limitation will have become progressively worse (FEV1 less than 50 percent but greater than 30 percent of predicted for a person of the same age with no lung disease). Your shortness of breath will increase, especially with even a small amount of exertion, and you will likely feel fatigued. Quality of life often diminishes during this stage.
• COPD Stage 4: This is very severe COPD; it means your airflow is severely compromised (FEV1 less than 30 percent predicted or less than 50 percent of predicted for a person of the same age with no lung disease). You also may have chronic respiratory failure that may lead to heart problems, such as heart failure. Your quality of life is markedly impaired, and COPD exacerbations may be life- threatening.

Originally published in 2016 and regularly updated.