A third of people recently diagnosed with asthma do not actually have the condition, research suggests.
Some people may be misdiagnosed with asthma while others may just have asthma that is no longer active, a new study found.
Experts led by a team at University of Ottawa carried out detailed breathing tests on 613 patients from 10 Canadian cities. All had been diagnosed with asthma in the past five years and every patient underwent a consultation with a lung specialist.
The findings showed that 33% of patients did not have active asthma. More than 90% were able to stop their asthma medications and remained safely off medication for a year.
Dr Shawn Aaron, lead author and respirologist at the Ottawa Hospital and professor at the University of Ottawa, 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impossible to say how many of these patients were originally misdiagnosed with asthma, and how many have asthma that is no longer active.
"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."
Overall, eight out of 10 patients who did not have asthma had been taking medication for it, while 35% took it every day.
The most common form of asthma medication is an inhaler but some people also need to take tablets. Side-effects of some of the medication, such as steroids, include high blood pressure, stomach upsets and lower resistance to infection.
The study also found that of those patients originally diagnosed with asthma, almost half (49%) had not undergone the required airflow tests, known as spirometry, to ensure the diagnosis was correct.
Instead, doctors had used their own observations and the patient's description of their symptoms to make a diagnosis.
Spirometry measures how much air you can breathe out in one forced breath.
Those patients found not to have asthma most often had other conditions instead. These included allergies or heartburn, while 28% had nothing wrong with them at all. Some 2% had serious conditions such as high blood pressure or heart disease.
In the UK, around 5.4 million people are currently receiving treatment for asthma - one in every 12 adults and one in every 11 children.
Dr Aaron said: "Doctors wouldn't diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an X-ray.
"But for some reason, many doctors are not ordering the spirometry 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."
The study was published in the Journal of the American Medical Association (JAMA).
ends
Dr Andy Whittamore, clinical lead for Asthma UK, said: "This small study suggests that some people may not be receiving the correct diagnosis for asthma or may be misdiagnosed.
"However, it does not address the equally worrying problem of under-diagnosis and poor control of asthma in the wider population.
"Nevertheless, the study highlights some important aspects of good asthma management and care, such as the need for people with asthma to receive objective measurements such as spirometry to confirm their diagnosis along with regular reviews with their GP or nurse.
"Asthma is a chronic condition with many complex causes which is why diagnosis may be difficult. Asthma is also a highly variable condition that can change throughout someone's life or even week by week, meaning treatment also needs to change over time.
"While some people may experience a remission in their asthma, symptoms may reoccur later and people should remain vigilant and aware of any new symptoms that may indicate a flare up of asthma.
"It is vital that no one with an asthma diagnosis stops taking their medication without discussions with their doctor first."
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules here