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Third of Adults Told They Have Asthma, Don’t Have It, Study Finds

Woman using asthma inhalerPhoto: Getty

Millions of North Americans are diagnosed with asthma, but new research finds that as many as one-third of adult patients may not actually have the respiratory disease. The study, published in January in the Journal of the American Medical Association, raises serious questions about how doctors are identifying the condition.

“Firstly, some patients were misdiagnosed in the community – meaning they never had asthma to begin with. Secondly, some had asthma, but it was inactive – meaning it was in remission,” respirologist Dr. Shawn Aaron, who led the research, explained in an interview with ResearchGate.

The study involved 613 patients randomly selected from 10 Canadian cities between January 2012 and February 2016. Although all said they had been diagnosed with asthma, a “current asthma” diagnosis was ruled out in 203 study participants – or 33 per cent of the group. In follow-up testing after a year, 30 percent still showed no evidence of asthma.

Furthermore, 12 participants had serious cardio-respiratory conditions that had been wrongly diagnosed as asthma.

One of the problems is that doctors prescribe asthma medication based on symptoms such as wheezing, coughing or shortness of breath, which are common occurrences when the airways are restricted. To make a proper diagnosis, patients need to take a series of lung function tests that measure airflow capacity.

That’s precisely what Aaron, a senior scientist at The Ottawa Hospital, and his fellow researchers did for this study. Participants were assessed with home peak flow and symptom monitoring, spirometry, and serial bronchial challenge tests. Some were weaned off asthma medication.

Asthma is complex – it’s difficult to diagnose and some patients have periods of remission. Aaron suggests that patients experiencing symptoms should ask for spirometry testing. If diagnosed with asthma, but later experiencing no symptoms such as shortness of breath or coughing, he would ask for reassessment.

Aaron told ResearchGate that he is concerned that patients may be taking medications they don’t need, which can be expensive and can lead to side effects over time. As well, they may have a cardiac or pulmonary disease that has not been diagnosed.

It’s estimated that 8 per cent of Americans, or around 25 million people, had asthma in 2009, according to the American Academy of Allergy, Asthma & Immunology. Statistics Canada states that about 8 per cent live with the condition.

View the study here.

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