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One-third of Canadian adults diagnosed with asthma don’t actually have it: study

Not all Canadian adult asthma sufferers actually have asthma
Over three million Canadians suffer from asthma and the rate of diagnosis is growing every year. But are we diagnosing correctly? Mike Drolet reports on a study that says a significant number of asthma patients could ditch their inhalers.

You’re short of breath and wheezing so you head to your doctor’s office where you’re diagnosed with asthma.

But a troubling new Canadian study suggests 33 per cent of adults recently diagnosed with asthma don’t actually have the condition.

The misdiagnosis may lead to patients taking medication they don’t need, or even worse, it could be hiding a more serious illness that should be addressed, scientists out of the Ottawa Hospital warn.

In some cases, the real culprit was an obstructed windpipe, heart disease or even allergies.

“I was seeing quite a number of patients being referred to my practice for asthma and when I saw them physically in clinic, I recognized they didn’t have asthma at all. I wondered how often this was happening in the community,” the study’s lead author, Dr. Shawn Aaron, told Global News. Aaron is an adult lung specialist and professor at the University of Ottawa.

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“Patients would come to me and I’d rule out asthma and find out they had something else very important that was missed,” he said.

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For Aaron’s study, he found 613 randomly selected Canadians who had been diagnosed with asthma in the past five years from 10 cities across the country. Aaron’s team scoured their medical records and worked with the patients for three months to test their breathing and look at their asthma medication to see if they could be weaned off the therapy.

Turns out, doctors ruled out asthma in one-third of patients. Over 90 per cent of these patients were able to stop their asthma medications and remain safely off the medication for one year.

Eighty per cent of patients who didn’t have asthma were taking medication and 35 per cent took it daily.

Doctors weren’t ordering breathing tests — called spirometry tests — to confirm their asthma diagnoses either.

“Doctors wouldn’t diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an x-ray. But for some reason, many doctors are not ordering spirometry tests that can definitely diagnose asthma,” Aaron said.

READ MORE: What doctors are warning parents about allergies and asthma in kids

What was triggering their breathing concerns? A bevy of situations cropped up: some patients had allergies or heartburn, two per cent had serious issues like pulmonary hypertension or heart disease, while two had an upper airway obstruction in which their windpipes were partially obstructed.

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“The patients were miserable and not responding to treatment for asthma because they didn’t have asthma,” Aaron said.

“Some people were frustrated that [misdiagnosis] happened to them but some were relieved to have an answer. If they didn’t have asthma they wanted to know what the real problem was,” he told Global News.

Inhalers are costly and come with a handful of side effects from rashes in the mouth, glaucoma, cataracts, tremors or a rapid heart rate. For those with asthma, the trade off is worth it but for people without the condition, they were taking on these side effects for no reason.

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Aaron is hopeful his findings will help doctors think twice about simply doling out a diagnosis without testing first. He’s also hopeful patients will pay attention and ask for a spirometry test to get the correct diagnosis.

About 8.5 per cent of Canadians aged 12 and over have been diagnosed with asthma, according to Statistics Canada data. In many cases, asthma is a life-long condition but sometimes it can become less active or go away entirely.

Aaron’s full findings were published Tuesday afternoon in the Journal of the American Medical Association.

carmen.chai@globalnews.ca