How Asthma Became One of the Most Overdiagnosed Diseases in Canada

Following a bout of pneumonia in 2014, 70-year-old Becky Hollingsworth experienced a persistent cough and shortness of breath. She didn’t wheeze or feel any chest tightness. Still, her doctor diagnosed her as having asthma, and prescribed two inhalers plus an oral medication. They eased her cough. She didn’t think much of the diagnosis until months later, when she received a phone call inviting her to participate in a study. As a retired nurse, Hollingsworth was an eager recruit.

The study, led by Shawn Aaron, who is a professor of medicine at the University of Ottawa and a respirologist at The Ottawa Hospital, was designed to investigate how often doctors overdiagnose asthma. Aaron had become increasingly alarmed by the number of patients who had been referred to him because their asthma medications weren’t working. When he retested such patients for the disease, he found that many did not, in fact, have asthma. He had already completed several smaller studies that suggested asthma overdiagnosis was surprisingly common. This new project was ambitious, involving 613 adults in 10 locations across the country—the largest such study to date.

Hollingsworth agreed to undergo repeated tests in Ottawa, an hour-long drive from her home near Arnprior, Ont. Aaron’s team first completed a simple, non-invasive procedure called spirometry—a test that Hollingsworth should have already undergone, but hadn’t. Wearing nose clips, patients exhale into a tube connected to a spirometer, a device that measures airflow, as fast and hard as they can for six seconds. After three blows, they inhale a bronchodilator—medication that relaxes muscles around the airways—wait 15 minutes and do three more blows. If the machine registers sufficient improvement in airflow, the diagnosis is asthma.

In Hollingsworth’s case, the bronchodilator made no difference, indicating she might not have the disease. But asthma symptoms can come and go. On a good day, a patient can do well on spirometry but still have the condition. Aaron therefore submitted all study participants who appeared asthma-free to a second test: the methacholine challenge.

Methacholine is a chemical that causes the airways to get twitchy and irritable. During the test, patients inhale increasing doses of methacholine and blow into a spirometer after each increase. A person with asthma will react badly and be hyper-responsive to low doses of the chemical.

The methacholine challenge is used when cases are difficult to diagnose. It takes up more lab time than spirometry and, because the chemical is expensive, costs more. But Aaron needed to be precise. For even greater certainty, he instructed participants who passed the methacholine challenge, thus indicating no asthma, to halve their medication over several weeks and then get retested. If the test was negative, he instructed patients to stop taking medication altogether and then test again in three weeks. Those who continued to show no signs of asthma were then assessed by a pulmonologist to determine what they actually had.

The results were stunning. About one-third of the participants—203 in total—did not have active asthma. (After 12 months of follow-up, that number declined slightly, to 181.) Sixty-one people had no symptoms at all, and almost as many only had allergies. Among the others, some suffered anxiety, while others had gastroesophageal disease (GERD). Several had serious cardiorespiratory disease, including ischemic heart disease, that had been missed. Hollingsworth had a post-viral infection cough linked to her previous pneumonia. She never did, and still does not, have asthma.

Aaron’s conclusions, published in the Journal of the American Medical Association in 2017, were consistent with earlier research in Canada, Italy, the Netherlands and Sweden. He is careful to note that asthma can go into remission and that a later discovery that it isn’t active doesn’t always signal a misdiagnosis.

At the same time, Aaron asked each study participant’s doctor to complete a questionnaire and medical-record review and provide evidence of spirometry, methacholine challenge or other objective tests employed in making the original diagnosis. Of the 530 physicians who responded, only half had requested any such tests. The other half had made the diagnosis subjectively, simply on the basis of what they observed in an office examination—suggesting a more systemic, and disturbing, problem.

It would be unthinkable to diagnose diabetes without ordering a blood test or to prescribe blood-pressure medication without wrapping a cuff around a patient’s arm to measure it. Yet many family physicians don’t order the standard test for asthma. As a result, nearly one-third of the three million adult Canadians estimated to have asthma may not have the disease after all.

Illustration: Anson Chan

Why Overdiagnosis is a Problem

Getting it wrong is not a trivial matter. Being labelled with a chronic illness can have psychological effects and hold people back from physical activity. Drugs have side effects, inhalers included. Typically, people with asthma use a corticosteroid inhaler daily and an emergency bronchodilator—such as the familiar blue puffer, Ventolin—if they have an attack. Prolonged use of steroids is associated with osteo­porosis, earlier cataract formation, glaucoma, easy bruising and skin thinning. And it can be tragic when misdiagnosis means a serious disease goes undetected.

Specialists have long argued that family physicians should not diagnose asthma without first ordering spirometry. Some general practitioners will administer the test in their own offices, but many find it impractical because, for one, the fees involved aren’t enough to cover the effort. In Ontario, the provincial health plan pays physicians about $24 to perform spirometry; British Columbia pays roughly $28; Saskatchewan, about $50. Some provinces, including Quebec, pay no fee at all.

Meanwhile, a high-quality, well-interpreted test takes time and expertise. Patients need coaching to do the test properly; the procedure can take half an hour. The machine spits out results, but they are meaningless if the physician is not experienced in decoding them. Clare Ramsey is an associate professor of respirology and critical care at the University of Manitoba. When she gets a referral, the first thing she does is make sure the patient actually has asthma. She sees some who’ve never had spirometry; others have had spirometry that “in no way looks like asthma” but led to a misdiagnosis because of poor interpretation.

The better option for GPs is to send patients to specialty lung-function labs, where spirometry is routine. But there are waiting lists. Those labs are usually in hospitals, where appointments aren’t easy to get. At Winnipeg’s Health Sciences Centre, for example, it can take six months to get a test.

Wait times can be an issue across the country. When a patient has trouble breathing and it looks like asthma, it’s expedient to offer medication and say, “Let’s try this and see if it helps.” Yet medication may improve breathing even if the patient doesn’t have asthma, so if a doctor doesn’t follow up with spirometry to confirm, the patient could be one of the thousands who end up living with the wrong diagnosis—and unnecessary suffering.

Access to Spirometry is Key

Rhonda Gould knows the frustration, and the harm, of waiting for a reliable diagnosis. She is a 58-year-old dental-administrative assistant living in North Vancouver who developed a lung infection in the spring of 2020, just as COVID-19 erupted. Her COVID-19 test was negative, and her infection was treated, but she was left with a rattling sound in her chest. By August, she was having difficulty breathing. A spirometry test did not indicate asthma, but her respirologist suggested she try inhalers, hoping they would provide some relief. She needed a methacholine challenge test to be certain about the asthma, but due to the pandemic, pulmonary-function labs were severely restricted in what they could do. She would have to wait—for months.

The breathing attacks continued through the summer, and in September, Gould’s family doctor, suspecting that her condition was triggered by fumes from the aggressive use of disinfectant wipes in the clinic where she worked, recommended she transfer to office duties. Her breathing improved, but on November 18, she was needed back in the clinic. By the end of the day, she could not get a breath and was panicking. “It was the scariest thing of my life,” she recalls. “I felt like I was choking.”

That evening, she made a desperate call to her respirologist, who helped calm her as she took puffs from her steroid inhaler. He told her to stay away from the wipes. Then he sent a referral to Chris Carlsten, head of respiratory medicine and director of the occupational lung-disease clinic at the University of British Columbia.

Carlsten was able to expedite the testing Gould needed. Finally, the following January, she had a second spirometry test, followed about two weeks later by a methacholine challenge, which confirmed the absence of asthma. Her respirologist also did a scope of her lungs and noted that her vocal cords were erratic and twitchy.

After reviewing the complete file, Carlsten concluded that she likely had an irritable larynx syndrome that could explain her reaction to the sanitation wipes. He recommended speech therapy to strengthen the muscles around her vocal cords. Gould was off work through that winter. When she returned in April, she was assigned to administrative duty, distanced from the clinic. “I had good care,” says Gould, resigned to the circumstances of the pandemic. But getting the proper diagnosis was a year-long ordeal—one that she hopes is a lesson for doctors when it comes to prompt and appropriate testing before diagnosing asthma.

Vancouver is one model for better access to spirometry. Over a decade ago, 17 hospitals agreed to use the same referral form, making it easier for patients to book appointments and choose the lung-function lab most convenient for them. Also, a special clinic attached to Vancouver General Hospital eliminates wait times for spirometry by providing walk-in tests to anyone with a doctor’s requisition. In 2019, the clinic reportedly saw 4,000 walk-ins. Still, access to spirometry remains a huge problem elsewhere in the province—and the country.

“We know that the need for spirometry is massive compared to what’s actually being done,” says Carlsten, who is also the director of Legacy for Airway Health, a new organization dedicated to the prevention and care of asthma and chronic obstructive pulmonary disease (COPD). He has tried for many years to educate family physicians about the importance of objective tests for asthma and agrees with Shawn Aaron that getting a spirometry test should be as easy as getting an X-ray for a broken bone. But it will take a cultural shift. Spirometry is, quite simply, undervalued. While Carlsten firmly believes that, if more labs offer spirometry, more family doctors will request it, he also thinks efforts may be better directed at educating the public so that patients know to demand the test.

The Risk of Underdiagnosis

Jazzminn Hein, for one, wishes she had known to ask for spirometry. She’d never heard of the procedure and didn’t know she actually had asthma. Her case presents a different consequence resulting from the lack of spirometry testing: underdiagnosis. Hein was always finding herself out of breath. She told herself it was because she was out of shape—and smoking didn’t help. She was only 24 but had started in her teenage years because “smoking was cool.”

Then she became pregnant, and the morning sickness was so severe she could barely eat, let alone tolerate a cigarette, and she quit. Her breathing didn’t improve. Her job in customer service for a telecommunications company required her to be on the phone a lot; by the end of a conversation, she’d be gasping. It was her previous anxiety diagnosis, her family doctor determined.

Then, one fall day in 2020, she and her mother-in-law packed her infant daughter into her stroller for a walk along the creek near her home in Maple Leaf, Ont. It was a jeans and T-shirt kind of day. As they went up a slight incline on the trail, she felt herself getting winded; when she reached the top, she was doubled over, with her chest burning and her lungs on fire. While she struggled for breath, her mother-in-law, a woman who’d smoked for 30-plus years, was doing just fine. Hein knew something was wrong. Another day not long after, she was so frightened by chest pain that she went to the hospital. It was just a panic attack, she was told, just her anxiety.

About a month later, Hein received a call from The Ottawa Hospital asking whether she had shortness of breath, a cough or wheezing, and if she would like to be part of a new study. She agreed. This time, Aaron wanted to find out how many people have asthma or COPD but haven’t been properly diagnosed. In November, Hein visited the study centre in Ottawa for the first of two spirometries. On her second visit, she met Aaron, who diagnosed her with asthma and sent her home with a prescription for inhalers.

Her quality of life has since dramatically improved. She’s able to exercise more, sleeps better and doesn’t have shortness of breath or chest pain. Knowing the true cause of her symptoms has also helped with her anxiety; there’s no need to panic over breathing problems. Her two-year-old daughter now has a baby brother.

Aaron expects to complete his large study, which involves about 4,000 people across Canada, by the end of this year and hopes to publish results by the end of 2023. Preliminary findings, after testing 2,400 people, revealed that eight per cent of study participants had undiagnosed asthma and 12 per cent had undiagnosed COPD. It’s more evidence that with a simple, cheap test, many lives would be different.

© 2021, Renée Pellerin. From “False Positive: Why Thousands of Patients May Not Have Asthma after All,” The Walrus (July 27, 2021), thewalrus.ca

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