A third of adults who’ve been diagnosed with asthma do not actually have the illness, new research suggests.
A study found that 33% of adults recently diagnosed with asthma by their physicians did not have active asthma when they underwent formal testing.
Over 90% of these patients were able to stop their asthma medications and remain safely off medication for one year.
The findings have called into question current methods used for asthma diagnosis both in the UK and abroad.
The study looked at more than 600 randomly selected patients, from 10 Canadian cities, who were 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 research 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% of these cases, physicians had not ordered the airflow tests required to confirm an asthma diagnosis. Instead, they based their diagnosis solely on the patient’s symptoms and their own observations.
Doctors in the UK use similar methods for diagnosing patients with asthma. According to the NHS website, asthma is “often” diagnosed by a GP, who will ask the patient:
whether they have typical symptoms of asthma, such as wheezing and breathlessness
when the symptoms happen and how often
whether they’ve noticed anything that might trigger their symptoms
if they have any conditions that often occur alongside asthma, such as eczema or hay fever.
Some patients will receive an asthma diagnosis after this initial session while others may be referred on for specialist breathing tests. However, the NHS says these tests “aren’t always practical”, so patients may be prescribed an inhaler to use for a short time to see if it helps.
According to the latest study, when the patients who were found not to have asthma were re-diagnosed, most had minor conditions like allergies or heartburn, and 28% had nothing wrong with them at all.
A total of 2% had serious conditions like pulmonary hypertension or heart disease that had been misdiagnosed as asthma and went on to receive the correct treatment.
“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impossible to say how many of these patients were originally misdiagnosed with asthma and how many have asthma that is no longer active,” said lead author of the study Dr Shawn Aaron, from the University of Ottawa.
“What we do know is that they were all able to stop taking medication that they didn’t need - medication that is expensive and can have side effects.”
Around 80% of the participants who did not have asthma had been taking asthma medication and 35% took it daily.
“Doctors wouldn’t diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an x-ray,” Dr Aaron added.
“But for some reason many doctors are not ordering the spirometry [breathing] tests that can definitely diagnose asthma.
“It wasn’t a surprise to most patients when we told them they didn’t have asthma.
“Some knew all along that their puffer wasn’t working, while others were concerned that they might have something more serious. Thankfully, the majority of the conditions were mild and easily treated.”
Retired nurse Becky Hollingsworth was diagnosed with asthma two years ago.
While participating in the study she learned that her shortness of breath was actually a temporary breathing problem left over from a bout of pneumonia.
“I was delighted we could verify that I did not have asthma,” said the 72-year-old grandmother.
“Even if it’s falsely diagnosed, you still have to deal with the consequences of having a chronic illness. You have to take medication and if you want to take a trip somewhere the insurance can be higher.”
The study is published in full in the Journal of the American Medical Association.