Finding Out Your COPD Stage

Early signs of chronic obstructive pulmonary disorder (COPD) include:

  • Cough that lasts for weeks or months
  • More mucus production than normal
  • Shortness of breath

How does someone find out their COPD stage?

If a person experiences these symptoms, they should report them to a healthcare provider as soon as possible. The healthcare provider will examine the symptoms and ask the person questions about his or her lifestyle, such as whether that person is a current or former smoker.

If the healthcare provider thinks that the person may have COPD based on the exam, some special breathing tests are the next step. These tests measure how healthy a person’s lungs are and how well they can breathe.

The tests have two important purposes:

  • They help the healthcare provider figure out whether or not the person has COPD.
  • If the tests show that the person does have COPD, then the results show which stage of COPD the person has.

What tests are used to determine COPD staging?

Two kinds of breathing tests called “spirometry tests” are used to figure out a person’s COPD stage. Both of these tests measure how well a person’s lungs function by taking two kinds of measurements1:

  • The largest possible amount of air the person can breathe out (called exhaling)
  • How quickly air can flow out of a person’s lungs

These two spirometry tests are called:

  • Forced vital capacity (also called FVC for short)
  • Forced expiratory volume in 1 second (also called FEV1 for short)

FVC spirometry test

The FVC test measures the total amount of air that a person can forcefully blow out of the lungs after taking in the deepest possible breath.

FEV1 spirometry test

The FEV1 test measures the total amount of air that a person can forcefully blow out of the lungs – in just 1 second – after taking in the deepest possible breath.

What happens during the spirometry tests?

The same machine is used to carry out the FVC and FEV1 tests, and the tests use the same basic technique. This machine is called “spirometer,” and it has an attached mouthpiece to blow into during the tests1.

The testing procedure is simple. The person being tested is asked to:

  • Inhale the deepest possible breath into the lungs
  • Exhale the breath by blowing into the mouthpiece as hard as possible

To make sure the results are correct, the person usually repeats the test several times.
A sensor in the machine measures the amount of air that the person can exhale at one time, and measures the speed of the air that flows out of the lungs.

What do the test results mean?

The results of the FVC and FEV1 tests are used to figure out the person’s COPD stage. The FVC and FEV1 results are compared in order to calculate a percentage, called the “FEV1/FVC ratio.” This percentage describes how well a person’s lungs work1,2.

Healthy people usually have a FEV1/FVC ratio of between 70% and 80%. This means that the flow of air out of their lungs is not blocked. If a person has a FEV1/FVC ratio of less than 70%, it shows that the flow of air is blocked, and he or she has COPD. The lower the percentage, the less effectively the lungs are working.

A person’s COPD stage depends on another kind of percentage, called the “predicted FEV1”. It compares a person’s airflow to the average airflow of other people of the same age, sex, and body type. The predicted FEV1 is a percentage that shows how well a person’s lungs are working compared to an average person with healthy lungs.

If a person’s predicted FEV1 is less than about 90%, then it shows that the airways are blocked due to COPD.

The predicted FEV1 percentage also shows a person’s current COPD stage:

  • COPD Stage I (Mild) = predicted FEV1 higher than 80%
  • COPD Stage II (Moderate) = predicted FEV1 between 50% and 80%
  • COPD Stage III (Severe) = predicted FEV1 between 30% and 50%
  • COPD Stage IV (Very Severe) = predicted FEV1 less than 30%

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Written by: Anna Nicholson | Last reviewed: July 2015.