Researchers did lung function tests on 613 adults who had been
diagnosed with asthma within the past five years. If participants
took asthma medicines, researchers gradually weaned them off the
drugs over four clinic visits to see how well their lungs worked
The evaluations ruled out asthma in 203 of the participants, or 33
percent. After one year of follow-up, 181 of these people still did
too well on lung tests to be diagnosed with asthma, researchers
report in JAMA.
“We were able to get these patients completely off asthma
medications, and they did well in follow up over the next year
despite remaining off medications,” said lead study author Dr. Shawn
Aaron of the University of Ottawa and the Ottawa Hospital Research
“Some of these patients were clearly misdiagnosed to begin with, and
they had other conditions other than asthma, and some did have
asthma but it was in remission,” Aaron added by email.
Asthma can be difficult to diagnose because not all patients have
the same triggers or symptoms, which can include difficulty
breathing, chest pain, cough and wheezing. Some chronic asthma
patients experience periods of remission and relapse.
For the current study, researchers had all of the patients monitor
symptoms and do breathing tests at home to see how fast air comes
out of their lungs, a measurement known as peak expiratory flow.
All of the participants also did bronchial challenge tests. For
these assessments, patients inhaled a medication that causes the
bronchial tubes to constrict, simulating conditions that can cause
asthma to see how well airways react.
Each patient also did spirometry tests that measure lung function by
seeing how much air people inhale, how much they exhale and how fast
Participants in whom a diagnosis of current asthma was ultimately
ruled out were followed up clinically with repeated bronchial
challenge tests over one year.
Among those misdiagnosed with asthma, 12 people, or 2 percent of the
participants, had serious conditions other than asthma, like heart
disease and pulmonary hypertension, the study found. Still others
were found to have conditions like chronic obstructive pulmonary
disease (COPD), gastroesophageal reflux (GERD) or anxiety-related
hyperventilation rather than asthma.
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Those who were misdiagnosed were less likely to have had airflow
limitation tests when they were originally diagnosed, compared with
participants who had their original asthma diagnosis confirmed in
the current study.
For patients who had asthma ruled out, 90 percent had asthma
medications safely stopped for one year after being weaned off drugs
for the study.
One limitation of the study is that researchers only followed
patients for a total of 15 months, which isn’t long enough to rule
out the possibility that some patients in remission might have
asthma symptoms in the future, the authors note. The study also
excluded patients using long-term oral corticosteroids, leaving only
people with milder forms of asthma to participated.
Still, the study reaffirms the need for patients who have been
diagnosed with asthma to have their diagnosis confirmed with
objective lung function testing, particularly spirometry, before
being started on lifelong therapy, Dr. Alan Kaplan, a researcher at
the University of Toronto who wasn’t involved in the study, said by
“The most important potential harm of misdiagnosis of asthma is not
treating the patient's actual disease,” said Dr. Helen Hollingsworth
of Boston University, co-author of an accompanying editorial.
“For other patients, not recognizing that asthma is in remission,
can lead to taking unnecessary medication,” Hollingsworth added by
email. “While the adverse effects of asthma medication are minimal,
no one wants to take unnecessary medication.”
SOURCE: http://bit.ly/2j5kfuD and http://bit.ly/2iDdxLa JAMA, online
January 17, 2017.
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