How to Distinguish Between COPD and Asthma

Senior man about to use asthma inhaler
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Chronic obstructive pulmonary disease (COPD) and asthma share a variety of common symptoms, which can make it difficult to distinguish between the two, at least initially. Because COPD has a certain stigma in our society that many patients do not like, some patients with COPD are more apt to say they have asthma. As with any condition, it's important to determine the correct diagnosis to ensure that you're getting proper treatment.


7 Differences Between COPD and Asthma

Symptoms Shared By COPD and Asthma

Both diseases may present these symptoms:

However, while the symptoms may be similar, there are enough differences that it is an important distinction to make.

Questions That Will Help Your Healthcare Provider Determine If You Have COPD or Asthma

Answers to the following questions will aid in a proper diagnosis of your condition.

Did I have symptoms of allergy or asthma as a child? 

While some patients are diagnosed with asthma in adulthood, most asthmatics are diagnosed in childhood or adolescence. In fact, a number of studies have shown that healthcare providers will often label older patients with asthma when in fact they have COPD. While COPD can be a long-term complication of poorly controlled asthma, COPD is rarely diagnosed before the age of 40.

What makes my symptoms worse?

Asthmatics can often identify what it is that worsens their symptoms. Things such as:

COPD, on the other hand, is often made worse by respiratory tract infections and not any of the asthma triggers mentioned above.

Am I a current or past smoker?

While COPD and asthma may occur together, COPD is more common in current or former smokers and those exposed to environmental tobacco smoke. While COPD can occur in patients that have never smoked, greater than 80% of patients with COPD smoked in the past or are current smokers.

Am I ever symptom-free?

Patients with asthma experience symptoms intermittently, are relatively symptom-free between asthma exacerbations and tend to experience significant periods of time without symptoms when their asthma is under good control. COPD patients, on the other hand, experience progressive symptoms and rarely go a day without symptoms.

Does my lung function return to normal between exacerbations?

In both asthma and COPD, your healthcare provider will measure certain aspects of your lung function with spirometry such as FEV1. With asthma, treatment returns your lung function to normal or near normal and you should not have many asthma symptoms between asthma exacerbations.

On the other hand, a COPD patient's lung function will generally not return to normal and only partially improves even with smoking cessation and bronchodilator treatment. In fact, even with smoking cessation, COPD patients may still experience a decline in lung function. This decline usually leads to symptoms, such as shortness of breath, that are often the reason the COPD patient is seeking care. Once a COPD patient develops symptoms, symptoms are generally chronic. Over time, COPD patients tend to experience symptoms that are not typical for asthma- losing weight, decreasing strength, endurance, functional capacity and quality of life.

The Overlap of Asthma and COPD

There is such a thing as overlap syndrome, known as asthma chronic obstructive pulmonary disease (ACOS).

COPD patients are increasingly noted to have an asthma component in addition to their COPD. Surprisingly, 1 in 4 asthma patients smokes and is at risk for COPD, like any other smoker.

Some COPD patients demonstrate asthma-like reversibility on pulmonary lung function testing referred to as an "asthma component." If reversibility is not present, no asthma component exists. The American Thoracic Society defines reversibility as a post-bronchodilator increase in FEV1 of at least 12% for both COPD and asthma. When reversibility is present, it is generally less in a COPD patient compared to a patient with only asthma.​​​

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By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.