According to the Center for Disease Control, 1 in 12 Americans have asthma and that number is on the rise. In the ten year span between 2001 to 2011, 28% more patients were diagnosed with the respiratory disease. Each year, an estimated 1.6 million people visit the ER with asthma as the primary diagnosis. But a new study has found that 1 in 3 patients diagnosed with asthma may not actually have the condition. 

The study

Canadian researchers recruited 613 men and women to participate in a study. Everyone in the group had been given an asthma diagnosis sometime within the last 5 years. Eighty percent of the study participants were taking asthma drugs like Singulair and Flovent and 35% of those patients were taking these medications on a daily basis.

Over a series of 4 visits, the scientists gave the participants several drug challenges to confirm or rule out an asthma diagnosis. One of the tests included a spirometry, which accesses how well a patient’s lungs work by measuring how much air they inhale, how much they exhale, and how quickly they exhale.

The findings

The respiratory experts behind the study found that 213 people, aka 1/3 of the group members, did not actually have asthma. Of those who were wrongly diagnosed, 90% were able to stop their asthma management medications completely and were completely fine after doing so for over a year. Many of these patients had minor conditions like allergies or heartburn instead of asthma and 28% had nothing wrong with them at all. The researchers noted that in about 2% of the cases, the patients were diagnosed based on symptoms alone and not clinical testing.

The study’s lead researcher, Dr. Shawn D. Aaron, a professor at the University of Ottawa, has a couple theories on why 1/3 of its participants were incorrectly diagnosed with asthma. “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,” he explains.

What does this mean?

The study authors concluded that: “Among adults with physician-diagnosed asthma, a current diagnosis of asthma could not be established in 33.1% who were not using daily asthma medications or had medications weaned. In patients such as these, reassessing the asthma diagnosis may be warranted.” In other words, if you have been diagnosed with asthma in the past, it can be beneficial to regularly reevaluate your symptoms with a doctor.

And if you suspect that you may have asthma and have not yet been diagnosed, it’s crucial that you go in for the correct testing to verify your diagnosis. It’s also important not to start a dosage of asthma medication before the results of the testing confirm your diagnosis. Dr. Aaron advised the New York Times that symptoms such as a cough or wheeze should not be enough to diagnosis a person as asthmatic or to put them on steroid inhalers. “If you have shortness of breath, wheeze or cough, you should suggest that the doctor order a spirometry test,” he said. “It’s a quick test with no risks or side effects that can predict asthma or other respiratory conditions,” he explained.

“This study underscores the possibility of over-diagnosis of asthma, and the importance of careful testing of pulmonary [lung] function to make a clear diagnosis before committing a patient to lifelong treatment,” adds Dr. Brian Christman, a spokesman for the American Lung Association.

The National Heart, Lung, and Blood Institute recommends the following types of tests to correctly diagnosis asthma:

Lung Function Test

Your doctor will use a test called spirometry to check how your lungs are working. This test measures how much air you can breathe in and out. It also measures how fast you can blow air out. Your doctor also may give you medicine and then test you again to see whether the results have improved. If the starting results are lower than normal and improve with the medicine, and if your medical history shows a pattern of asthma symptoms, your diagnosis will likely be asthma.

Additional Testing

Your doctor may recommend other tests if he or she needs more information to make a diagnosis. Other tests may include:

  • Allergy testing to find out which allergens affect you, if any.
  • A test to measure how sensitive your airways are. This is called a bronchoprovocation test. Using spirometry, this test repeatedly measures your lung function during physical activity or after you receive increasing doses of cold air or a special chemical to breathe in.
  • A test to show whether you have another condition with the same symptoms as asthma, such as reflux disease, vocal cord dysfunction, or sleep apnea.
  • chest x-ray or an EKG (electrocardiogram). These tests will help find out whether a foreign object or other disease may be causing your symptoms.