In a multicenter cohort study that enrolled 701
randomly selected adults with physician-diagnosed
asthma, current asthma was excluded in 33% of the
613 participants who completed the study.
The study set out to determine whether a diagnosis
of current asthma could be ruled out and asthma
medications safely stopped in randomly selected
adults with physician-diagnosed asthma.
Dr Shawn Aaron from the University of Ottawa
recruited 701 adults who had been diagnosed with
asthma within the past five years from the community
and brought them into their labs and ran extensive
lung function tests on them to try to prove asthma.
If researchers could not show evidence of asthma,
they 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.
They 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.
There are two reasons for this.
Firstly, some patients were misdiagnosed in the
community Ė meaning they never had asthma to begin
Secondly, some had asthma, but it was inactive Ė
meaning it was in remission.
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
If they donít order the tests, they are more likely
to get the diagnosis wrong, researchers found.
Ultimately misdiagnosis leads to treatment with the
wrong medications that will have side effects
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 donít
have), anxiety, unnecessary lifestyle alterations,
and a lost opportunity to diagnose the true cause of
the patient's complaints.
Scientists found two percent of randomly selected
patients had serious cardiac or pulmonary diseases
that had been misdiagnosed as asthma.
Doctors should always order spirometry and
appropriate lung function tests in anyone they
suspect to have asthma and should also try to follow
asthma treatment guidelines and reassess and taper
asthma medications in patients who have been
controlled for three months.
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
Of 701 participants 613 completed the study and
could be conclusively evaluated for a diagnosis of
Current asthma was ruled out in 203 of 613 study
Twelve participants (2.0%) were found to have
serious cardiorespiratory conditions that had been
previously misdiagnosed as asthma in the community.
After an additional 12 months of follow-up, 181
participants continued to exhibit no clinical or
laboratory evidence of asthma.
The longer they live in Canada the more new
immigrants allergy rates increase (2017-01-30)
For more information
Reevaluation of Diagnosis in Adults With
The University of Ottawa