The Dose22:03How do I know if I have asthma?

Asthma may be one of the most common chronic diseases in Canada, but experts say it can be tough to diagnose. 

“The best way to make a diagnosis of asthma is to have a patient do breathing tests,” Dr. Shawn Aaron, a respirologist at the Ottawa Hospital, told Dr. Brian Goldman, host of CBC’s The Dose

The standard test is a lung function test, done using a device called a spirometer, said Aaron. 

During the test, a patient’s lung capacity is measured by seeing how quickly and forcefully they can blow air into a tube. 

Aaron said despite being a perfect way to diagnose asthma, lung function testing can be hard to access, “even though the test only takes 20 or 30 minutes, it’s perfectly safe, and it only costs about $40.” 

Many may think of asthma as a childhood condition. Though asthma does affect more children than adults in Canada, about nine per cent of adults live with the condition, and experts say misdiagnosis and underdiagnosis are both big issues.”

Some governments restrict access to testing, said Aaron, and patients often have to travel to a hospital to get it done. 

Dr. Chris Carlsten, a professor of medicine at UBC and director of the non-profit Legacy for Airway Health, said the lack of spirometry testing is “a huge problem.” 

“I’ve heard directly from doctors who said, ‘Yeah, we know that you need this testing, but it’s hard to get. So I’m just going to make the diagnosis anyway,’ which is really against all the standards,” said Carlsten. 

A woman with white hair and glasses blows into a plastic tube.
A woman carries out a spirometry test at the Ottawa Hospital. The test measures lung capacity to determine whether someone has asthma or chronic obstructive pulmonary disease (COPD). (CBC)

Travel time to get to a clinic, language barriers and low health literacy can all affect access to testing, said Carlsten.

He’d like to see lung function tests become as easy to get as blood tests. 

“People can go get their blood work anywhere, then they should be able to get this spirometry test anywhere,” he said. 

What are the symptoms of asthma? 

Common symptoms of asthma include wheezing, shortness of breath, chest tightness and cough. 

Those symptoms can overlap with other conditions, however, which is why experts say the lung function test is key. 

Aaron has done two Canadian studies that found a significant proportion of people are either misdiagnosed with asthma, or go undiagnosed. 

The first study recruited people who had been diagnosed with asthma in the previous five years. 

“We found that 30 per cent of people who were labelled with asthma had no evidence of active asthma when we tested them and withdrew their asthma medicines,” said Aaron. 

For the second study, Aaron and his team randomly recruited Canadian adults who were complaining of symptoms such as shortness of breath, cough, or wheezing — but who had not been given a diagnosis related to these symptoms — then tested them for asthma or chronic obstructive pulmonary disease (COPD). 

Aaron and his team found that 20 per cent of their test subjects had evidence of asthma or COPD after doing lung function tests. 

Population-level studies suggest that about four to five per cent of Canadians are likely living with undiagnosed asthma, said Aaron. 

Some symptoms are sneaky

It can be “super challenging” to know if you have asthma, said Dr. Andrea Gershon, a respiratory physician and scientist at the Sunnybrook Health Sciences Centre and the University of Toronto. 

“That’s why if you have symptoms, it’s good to go talk about it with your doctor,” said Gershon.

There are also sneakier symptoms, said Aaron, including waking up regularly in the middle of the night with a cough, shortness of breath, or wheezing.   

“We know that asthma is very sensitive to corticosteroids and our body produces steroids naturally from our adrenal glands, but these steroid levels actually fall to the lowest level around 3 o’clock or 4 o’clock in the morning,” said Aaron. 

If your asthma is uncontrolled, you may wake up around that time with symptoms, he said. 

What causes asthma? 

Experts say it’s hard to tell for sure. 

“I don’t think anybody really knows what causes asthma. It’s a highly prevalent disease, and sometimes people will get it and we just have no idea why,” said Gershon. 

Experts say there are definite risk factors for asthma, however, including allergens, air pollution and workplace exposures to fumes or chemicals. 

And climate change could be making asthma worse. 

“As our climate warms, that is obviously going to prolong the allergy season so that there’s going to be more tree and grass pollen in the air, and there’s going to be more ragweed pollen in the fall,” said Aaron. 

For years asthma has been becoming more prevalent in Canada though some experts say we may have now reached a plateau. 

“The concern is that we could have another wave of increase with climate change because of all the allergens that are increasing,” said Carlsten. 

“We are seeing more people coming in complaining of allergy season in general; the allergy season is longer, generally more intense.” 

Another risk factor for asthma is obesity, with asthma being about twice as common in adult women with a body mass index over 30, said Aaron. 

“We don’t know why that is, but we think that fat cells may actually provoke asthma by secreting inflammatory mediators,” he said. 

“So part of the reason why asthma may be more common is simply because we have more obesity in our society.” 

How is asthma treated? 

For most asthmatics, the condition can be controlled using inhaled steroids, sometimes combined with bronchodilators that open up the airways, said Aaron. 

About five per cent of patients have severe asthma that is harder to control, but a number of newer drugs are making life easier for those patients, said Aaron. 

Among them are monoclonal antibodies, usually given by injection once a month or every two weeks, he said. 

“The problem is they’re expensive. They’re $40,000 a year. But for the appropriate patient whose asthma can’t be controlled with inhaled steroids and long-acting bronchodilator medications, these medicines are really life-changing,” said Aaron. 

Experts say if you suspect you might have asthma, talk to a health-care provider. 

“It is very important to get the proper testing, since it is commonly misdiagnosed, which can lead to unnecessary medications,” said Carlsten.

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