Third of adults diagnosed with asthma may not have it: study

One third of people with asthma may not actually have the condition either because it has got better, or they were wrongly diagnosed in the first place, a new study suggests.
The study found that 33 per cent of adults recently diagnosed with asthma by their physicians did not have active asthma.
Over 90 per cent of these patients were able to stop their asthma medications and remain safely off medication for one year, researchers said.
"It's impossible to say how many of these patients were originally misdiagnosed with asthma, and how many have asthma that is no longer active," said lead author of the study, Shawn Aaron, professor at the University of Ottawa in Canada.

"What we do know is that they were all able to stop taking medication that they did not need - medication that is expensive and can have side effects," Aaron said.
Eighty per cent of the participants who did not have asthma had been taking asthma medication, and 35 per cent took it daily.

The study also found that doctors often did not order the tests needed to confirm an asthma diagnosis. Instead they based their diagnosis solely on the patient's symptoms and their own observations.
"Doctors would not diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an X-ray," said Aaron.

"But for some reason many doctors are not ordering the spirometry tests that can definitely diagnose asthma," he said.
The study looked at 613 randomly selected patients from 10 Canadian cities diagnosed with asthma in the last five years.
After a series of detailed breathing tests followed by consultation with a lung specialist, asthma was ruled out in a third of these patients.
The team was able to access the medical records of 530 of the patients to see how they were originally diagnosed. They found that in 49 per cent of these cases, physicians had not ordered the airflow tests required by medical guidelines.

When the patients that were found not to have asthma were re-diagnosed, most had minor conditions like allergies or heartburn, and 28 per cent had nothing wrong with them at all.
Two per cent had serious conditions like pulmonary hypertension or heart disease that had been misdiagnosed as asthma, and went on to receive proper treatment.
"It was not a surprise to most patients when we told them they did not have asthma," said Aaron.
"Some knew all along that their puffer was not working, while others were concerned that they might have something more serious. Thankfully, the majority of the conditions were mild and easily treated," he said.

The study confirms and expands on Aaron's 2008 study which suggested that 30 per cent of asthma patients had been misdiagnosed.
The study was published in the Journal of the American Medical Association.