Asthma diagnosis often wrong, study reveals
Study found most patients continued taking medication — sometimes daily — despite not having the condition
A new study published in the Journal of the American Medical Association (JAMA) found 33 per cent of adults recently diagnosed with asthma by their physicians did not have an active form of the respiratory condition.
The clinical study, led by Dr. Shawn Aaron, senior scientist and respirologist at The Ottawa Hospital and a professor at the University of Ottawa, enlisted 701 participants who were diagnosed with asthma in the last five years, randomly selected from 10 Canadian cities.
The new research expands on the findings of a previous study conducted by Aaron in 2008.
"There's two reasons why in our study we didn't find asthma," said Aaron. "Some of the patients had actually had asthma but their asthma had gone into remission. Asthma is a disease which can relapse and remit. In other words, it can get spontaneously better on its own."
Aaron said at least 20 per cent of study participants likely had asthma at one point, but the disease had disappeared over time.
Kept taking medication
"Many of these patients were still being treated with asthma therapies on a daily basis. So, they were being over-treated," Aaron said.
The second reason for not finding asthma in the subjects, according to Aaron, is that they never had it in the first place.
Many of these patients were still being treated with asthma therapies on a daily basis. So, they were being over-treated.- Dr, Shawn Aaron
"In other words, they were misdiagnosed by their physician," he said.
Aaron said it's impossible to say how many of the subjects were misdiagnosed, and how many had asthma but no longer do.
"What we do know is that they were all able to stop taking medication that they didn't need, that is expensive and can have side effects," Aaron said.
Aaron said while asthma medications are generally easily tolerated, they can have side-effects including an infection known as oral thrush and easy bruising. Long-term side-effects can include osteoporosis, cataracts or glaucoma, and some asthma medicines will cause rapid heart rate, anxiety and tremors, Aaron said.
Misdiagnosis, missed opportunities
With misdiagnosis, Aaron said, doctors lose the opportunity to properly identify the true cause of a patient's symptoms.
"We found that in two per cent of the patients [there were] serious cardiac or respiratory conditions that had been misdiagnosed as asthma. These people were suffering and they weren't getting better because the physician that made the diagnosis had gotten it wrong."
The study also concluded that doctors often do not order the proper tests needed to confirm an asthma diagnosis, and instead base their conclusions solely on their own observations of a patient's symptoms.
"The message that we want to get out to the community, both to patients and doctors, is if you have respiratory symptoms — that is — if you're short of breath, or you're wheezing, or you're coughing and you see your doctor, insist on having a spirometry test," Aaron said.
Patients should demand test
Spirometry is a test used to assess how well lungs function by measuring how much air is inhaled and exhaled, and how quickly. It's used to diagnose asthma and chronic obstructive pulmonary disease (COPD).
"Insist on doing the test to confirm the diagnosis prior to treatment," said Dr. Aaron.
The retired nurse from Braeside, Ont., just west of Arnprior, said when she got over her illness, she continued to experience shortness of breath and coughing.
After examining her symptoms and reviewing her medical history, Hollingsworth's family doctor diagnosed her with post-infection asthma and put her on medication.
"I was really sorry to hear that because no one wants to have a chronic illness," said Hollingsworth, who was concerned about both the cost and side-effects of the drugs she was taking.
"If you want to travel and you talk to the insurance companies they put your rates up because you have a chronic illness," she said.
'Doctors can't know everything'
After participating in Aaron's clinical trial a few months after her asthma diagnosis, Hollingsworth discovered that she did not have the disease and was simply recovering from an acute lung infection.
"We found out very quickly that I didn't have asthma because in the clinical trial, they give you medication that will bring on an asthma attack if you have asthma. I never did have an attack."
Hollingsworth said she doesn't blame her family doctor for getting her diagnosis wrong.
"I didn't think ill of my doctor. I know that doctors can't know everything. But I did think that spirometry tests could be made available in [general practitioners'] offices, which would be a lot cheaper than putting people on medications."