When Does Asthma Become COPD?
COPD is an umbrella term. Emphysema and chronic bronchitis are the most common diseases to fall under this umbrella. But, sometimes asthma qualifies. So, when does asthma qualify as COPD? Here’s what to know.
In an earlier post I explained “Connections between asthma and COPD.” I explained that one of those connections is “Airflow limitation.” What I did not explain to you is when asthma becomes COPD. And that’s what I will attempt to do here.
Diagnosing asthma and COPD with PFT
So, if you read those, you know what an FEV1 is. You know how this can be used to determine if you have COPD. Still, here’s a quick review. You do a PFT. You do a pre and post FVC. A computer determines your FEV1. This is the best indicator of airflow limitation.
You then use a bronchodilator. This can be either an inhaler or breathing treatment. Then you do a second FVC. Here’s how you determine if it’s asthma or COPD.
- COPD. By it’s basic definition, it’s “persistent respiratory symptoms and airflow limitation.” Your pre and post bronchodilator FEV1 is less than 80%. Your post bronchodilator FEV1 is not much different than your pre bronchodilator FEV1. This shows that airflow limitation is persistent. It is not reversed with time or treatment. This confirms a diagnosis of COPD.1
- Asthma. By it’s basic definition, respiratory symptoms and airflow limitation are intermittent and vary in intensity. Asthma attacks are reversible with time or treatment. Your post bronchodilator FEV1 improves by 12% or more. This shows airflow limitation is reversible. This can help make a diagnosis of asthma. 2
- Asthma and COPD. This is when you have both. Your airflow limitation is reversible. But, your FEV1 remains under 80% despite treatment.
When can asthma become COPD?
Check out these statistics. About 90-95% of asthmatics can obtain good asthma control. Most asthmatics should have normal lung function between asthma attacks. This means their FEV1 should reach 80% or greater.2,3
But, this is not always the case. About 5-10% of asthmatics have what is called refractory asthma. This is asthma that does not improve with treatment. They continue to have airflow limitation and respiratory symptoms despite treatment. These asthmatics are now classified as having Severe Asthma.2,3
Some of these asthmatics may also be diagnosed with COPD.2
Why do some asthmatics develop COPD?
Researchers are still investigating this area. They are still not sure. But, one theory is the type of inflammation involved. Most asthmatics have inflammation caused by white blood cells called eosinophils. So, they have eosinophilic inflammation. This type of inflammation responds well to traditional asthma medicines.
Their asthma responds well to beta 2 adrenergics and corticosteroids. A daily dose of medicines like Advair or Symbicort help them obtain good asthma control.
When these medicines don’t work, they may be diagnosed with Severe Asthma. The cause may be a different type of inflammation, such as neutrophilic inflammation. This is similar to the type of inflammation seen in COPD airways.
Plus, Severe Asthmatics may have airway scarring. Inflammation can cause damage to airway tissues. Tissues then become scarred. This scar tissue makes airway walls thicker. This also is similar to what happens with COPD.
Thicker walls make airways abnormally narrow. There is no medicine for treating this. And this may cause persistent airflow limitation. When this happens, a diagnosis of COPD can be made. It may result in a diagnosis of Asthma/ COPD Overlap Syndrome.
The importance of a good treatment regimen
Researchers are still working hard to understand all of this. There are many similarities between asthma and COPD. Having a duo diagnosis of asthma and COPD may complicate treatment. But, it can be treated by seeing a qualified doctor and developing a good asthma/COPD treatment regimen.
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