How asthma became one of the most over-diagnosed diseases in Canada

OUT OF BREATH

- Renee Pellerin

FOLLOWING ABOUT 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.