Debunking asthma diagnoses

Mar 25, 2017

You've heard it before in a wheezy cough or the puff of an inhaler. Asthma is a common inflammatory disease. It is estimated that one in every thirteen adults is affected by asthma, which comes out to roughly 17 million people, according to the Centers for Disease Control. But in a new study published by the Journal of the American Medical Association, researchers found that 33 percent of diagnosed patients did not, in fact, have the disease.

To understand more about these findings, “Take Care” was joined by the author of this study, Dr. Shawn Aaron. Aaron is a professor in the Department of Medicine at the University of Ottawa, and a senior scientist at Ottawa Hospital Research Institute in Ontario, Canada.  


Asthma, Aaron explains, is a disease of the airways whereby inflammation causes irritation and twitching. This inflammation can manifest through swelling, redness, and mucus production, which in turn makes the muscles around the airway extremely sensitive. This hypersensitivity leads to constriction of the airway, which gives rise to asthma symptoms as we recognize them: difficulty breathing, wheezing, coughing, and in more severe cases, asthma attacks.

Asthma is often seen during childhood, which is when symptoms commonly begin to surface. Fortunately, children diagnosed with asthma are more than likely to outgrow it after adolescence, with roughly 75 percent of those children eventually becoming asymptomatic. However, this doesn’t mean adults are in the clear. Asthma does not discriminate by age. Some patients, Aaron says, will never experience symptoms in their life, but start to show signs of onset asthma in their 70s.

So what causes it exactly? According to Aaron, asthma is more common in people with allergies. Roughly half of asthmatics are referred to as allergic asthmatics, meaning those who experience asthma as a response to allergens in their environment. Those who cannot identify a trigger to their asthma are referred to as non-allergic asthmatics, and Aaron explained that doctors do not entirely understand the cause of the inflammation in those individuals.

Regardless of the cause, asthma remains a common issue for many patients. However, it would appear that it isn’t a problem for as many people as originally thought. Aaron and his colleagues discovered this through their study, inspired by the many patients who thought they had asthma but didn’t. With so many instances of misdiagnosis or symptom relief, Aaron wanted to see the numbers. And sure enough, of 613 patients who were diagnosed with asthma within the past five years, 33 percent no longer had active asthma symptoms.

Asthma is a disease that can relapse and remit over time, Aaron says. So, the entire 33 percent was not necessarily misdiagnosed, as some could actually be in remission. Still, there had been many individuals referred to Aaron with asthma diagnoses who had entirely different causes behind their breathing problems. From side effects to various medicines, to coronary artery disease, many asthma-like symptoms were not caused by asthma at all.

For this reason, Aaron mentions the importance of the spirometer, a tubular instrument which measures how quickly, and how much air, a patient can exhale. Asthma can be diagnosed subjectively through a patient’s symptoms, but the only definitive test that ensures a legitimate diagnosis requires the use of the spirometer.

A spirometer, which is used in testing for asthma.
Credit andersonjames250 / Flickr

Startlingly, Aaron found that only half of the participants in the study had actually taken the spirometer test, which offers some insight into how 33 percent of those diagnosed could be asymptomatic. This poses a problem for those misdiagnosed, as asthma medication is costly and there is potential for harmful side effects.

Despite the results of the study, Aaron stresses that patients should not stop taking their asthma medication if they are skeptical about their diagnosis, because this could provoke an asthma attack. Rather than quitting cold-turkey, if you are not experiencing symptoms, ask your doctor about taking a spirometer test. If the results indicate that your lung functions are normal, you and your doctor can decide if tapering down your asthma medicine is the right thing to do.