Though asthma is one of the most common respiratory conditions around the world, a new study suggests it may be overdiagnosed. The study – which was published in the journal, JAMA – found that over one third of asthma patients could be misdiagnosed.
Asthma is a chronic condition in which inflammation in the lungs impairs breathing. It’s estimated that 25 million people in the US have been diagnosed with asthma, with around 300 million people being affected by the condition, worldwide.
In studying the incidence of asthma, researchers at the University of Ottawa in Canada followed 613 patients who had been diagnosed with asthma in a five-year period. Using a home peak flow meter, spirometry and serial bronchial challenge tests, the researchers sought to determine whether each patient’s asthma diagnosis could be confirmed.
The researchers found that 203 of the patients were misdiagnosed – just over 33 percent of the study participants. Importantly, most of these patients in which asthma was ruled out were able to stop using their prescribed asthma medications with no adverse effects for 12 months.
Twelve of the study participants were diagnosed with serious cardiorespiratory illnesses which could have been mistaken for asthma. According to the study coordinators, 28 percent of the patients with misdiagnosed asthma were not found to have any respiratory disease at all. The majority of participants were, in fact, found to have minor medical issues, including heartburn and allergies.
“It is impossible to say how many of these patients were originally misdiagnosed with asthma, and how many have asthma that is no longer active,” said Dr. Shawn Aaron, respirologist at The Ottawa Hospital, and a professor at the University of Ottawa. “What we do know is that they were all able to stop taking medication that they did not need – medication that is expensive and can have side effects.”
Aaron and his colleagues admit that some patients may have initially suffered from asthma, however the disease spontaneously resolved itself before the beginning of the study. Still, they say that up to 21 percent of the patients could have been misdiagnosed with asthma.
The researchers also found that nearly half of the patients were not diagnosed with asthma as a result of objective procedures such as bronchial challenge testing and spirometry. This finding suggests that tools used to diagnose the condition may be underused, resulting in false diagnoses.
“Doctors would not diagnose diabetes without checking blood sugar levels, or a broken bone without ordering an X-ray,” said Aaron. “But for some reason, many doctors are not ordering the spirometry tests that can definitely diagnose asthma.
“We need to educate physicians and the public to get the diagnosis right in the first place. Patients who have difficulty breathing should ask their doctor to order a breathing test – spirometry – to determine if they might have asthma or even chronic obstructive pulmonary disease.”
“Similarly, if patients think they may have been misdiagnosed with asthma or that they no longer have asthma, they should ask their doctor for a spirometry test. Asthma can be deadly, so patients should never go off their medication without speaking to a doctor first.”