COPD Severity on Lung Function Tests
Dear Dr. Mahler:
I want to learn more about COPD severity. On the breathing tests, there are numbers to tell how well you are breathing. I’m still confused with moderate, severe, to very severe and what it means. Thanks.
Joseph of Kansas City, MO
Your question about COPD severity is a common concern among many patients that I see in my practice at Valley Regional Hospital.
First, the grading of severity is based on how much air that you exhale in one second. This is abbreviated FEV1. Here is a graph that shows what FEV1 represents.
Your best value is then compared with what it is expected to be for someone your age, sex (female or male), and your height. This is called FEV1 percent predicted.
To add to the complexity of the grading of severity of COPD, testing should be performed before and after inhalation of a bronchodilator. Albuterol is almost always used for testing. This is called post-bronchodilator FEV1 percent predicted. Your health care provider may or may not order testing with albuterol.
Guidelines and strategies for COPD describe the following four grades for COPD based on breathing tests:
Post-bronchodilator FEV1 percent predicted
MILD 80% or higher
MODERATE 50 to 79%
SEVERE 30 to 49%
VERY SEVERE less than 30%
It is important to remember that your current inhaled bronchodilators can affect the results of testing. For example, if you took your inhalers at 8 am and had testing at 10 am, this likely represent the peak effect of many long-acting bronchodilators. However, if the testing is done at 3 pm, the results will not be as good.
As you can see, higher numbers for lung function are better. However, it is important to recognize that the test results are just numbers and don’t reflect how you feel or how you are breathing.
These grades are most useful in describing the types of patients with COPD in research studies. It allows comparison of different medications in similar types of individuals based on breathing test results.
Joseph – I hope that this information is helpful. Finally, you can move up or down in these grades based on more effective treatments (may go up) or following a flare-up or exacerbation (may go down).
Donald A. Mahler, M.D.
Diagram of spirometry to diagnose COPD. FEV1 is the amount of air exhaled in one second.