No asthma found in one third of adults previously diagnosed with it

Researchers blame the high number on misdiagnosis and spontaneous remission.

For those diagnosed with asthma within the past five years, a JAMA study has found a current diagnosis could not be established in about one third of supposed asthma sufferers. We talked to the study’s lead author, Dr Shawn Aaron from the University of Ottawa, to find out what doctors and patients should do to ensure they’re not getting misdiagnosed.

ResearchGate: Could you briefly introduce your study and findings?

Shawn Aaron: Our study set out to determine how often we could confirm or alternatively rule out active asthma in adults who had recently been diagnosed by physicians. We recruited 701 adults who had been diagnosed with asthma within the past five years from the community. We brought them into our labs and ran extensive lung function tests on them to try to prove asthma. If we could not show evidence of asthma, we then had the patients start to taper their asthma medications and kept following them and re-testing them with bronchial provocation tests to try to show asthma. We also sent them to a pulmonologist to try to determine if there were other explanations for their symptoms apart from asthma. Ultimately, 33 percent of the participants were found not to have active asthma, despite being completely off medications.

RG: Why do you think you were unable to find asthma in so many previously diagnosed patients?

Aaron: There are two reasons for this. Firstly, some patients were misdiagnosed in the community – meaning they never had asthma to begin with. Secondly, some had asthma, but it was inactive – meaning it was in remission.

RG: What makes asthma so difficult to diagnose?

Aaron: A lot of other diseases can present with cough, shortness of breath, and wheeze. For instance, serious diseases like congestive heart failure or pulmonary embolism can present with these symptoms, as well as much less serious diseases like allergic rhinitis or heartburn. Asthma is not that difficult to diagnose, but doctors must order the proper tests to make the diagnosis correctly. If they don’t order the tests, they are more likely to get the diagnosis wrong, we found.

RG: Could diagnosing someone with asthma who doesn’t have it be harmful? If so, how?

Aaron: Ultimately misdiagnosis leads to treatment with the wrong medications that will have side effects without benefits. This includes the cost of unnecessary asthma medications (an average of up to $1200 per year), the side effects of unnecessary medications (including oral thrush, easy bruising, osteoporosis, cataracts, glaucoma, tremor), insurance problems (being diagnosed with a chronic disease you don’t have), anxiety, unnecessary lifestyle alterations, and a lost opportunity to diagnose the true cause of the patient's complaints. We found two percent of our randomly selected patients had serious cardiac or pulmonary diseases that had been misdiagnosed as asthma.

RG: Do your findings have implications for how doctors should diagnose asthma?

Aaron: They have two main implications. Firstly, doctors should always order spirometry and appropriate lung function tests in anyone they suspect to have asthma. Secondly, doctors should also try to follow asthma treatment guidelines and reassess and taper asthma medications in patients who have been controlled for three months.

RG: What advice do you have for patients who’ve been diagnosed with asthma?

Aaron: Patients should make sure they get breathing tests (spirometry) done before they accept a diagnosis of asthma if they are having trouble breathing. Secondly, if they have been diagnosed with asthma and are well-controlled (in other words, they are not having shortness of breath or wheezing or coughing) they should ask their doctor to reassess the diagnosis with spirometry and then decide whether they can try tapering asthma medication out. They should only do this with their doctor, not alone.

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