As many as 30% of people diagnosed with asthma don't have the disease, newly published research suggests.
Using spirometry and bronchial challenge tests with methacholine, researchers at the University of Ottawa tried to confirm physician diagnoses of asthma in 496 people from eight Canadian cities. Asthma was excluded in 150 subjects within four follow-up visits. Two-thirds of that group were safely able to discontinue their asthma medication within six months (CMAJ. 2008;179:1121-1131).
“This is a serious issue because an inappropriate diagnosis may obscure the true cause of a patient's symptoms,” noted lead author Shawn Aaron, MD, a senior scientist at the Ottawa Health Research Institute.
A related editorial by Matthew Stanbrook, MD, and Alan Kaplan, MD, and the CMAJ editorial team agrees and cautions that asthma may be misdiagnosed rather than overdiagnosed. Symptoms attributed to asthma may signify other underlying medical conditions. They agree that all suspected cases of asthma must be diagnosed with spirometry, which should be available in all practice settings.