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Column originally published Apr 26, 2016
Column last revised/updated on Jul 22, 2018

Over-Diagnosis Of Asthma

Question: I just heard in the news that asthma is being over-diagnosed, and unnecessary treatment can be harmful. I am really scared. Our four-year-old son was diagnosed with asthma. He was constantly sick with colds, always congested in his nose and his chest; he coughs when he runs. Sometimes, he gets out of breath and has to stop running. His doctor gave him two puffers which he takes every day. He is much better now. Should I ask his doctor for tests to confirm whether he has asthma?


When I heard about this report, I was concerned that parents like yourself will get confused. Asthma is one of the most common medical conditions in children and adults. It is still often under-recognized, under-diagnosed and under-treated. That is why I am worried about claims of over-diagnosis and over-treatment.

Most often, people relate tightness of the chest and wheezy noise as symptoms of asthma. However, many children only have cough and chest congestion. Wheezing may not happen at all, or only when the child is sick with a cold. Many children have cough when they run. The cough may not be too severe unless the child is sick with a cold.

Children with asthma have inflammation of the bronchial tubes; these tubes react to things that they are allergic to: dust mites, mould, or pet dander. Their symptoms can be seasonal or everyday. Their cough and chest congestion are worse when they contract viral infections.

Cold symptoms usually last a few days in normal healthy children. However, if a child is sick for weeks, or if one cold runs into another, this is not simple colds any more. There can be underlying asthma which prolongs cold symptoms.

Asthma is traditionally diagnosed with lung function test. One has to blow into a machine as fast, as hard, and as long as possible for several times, and repeat it after taking several puffs of medicine that relaxes the muscle around bronchial tubes. If there is significant increase in airflow after the puffer, the diagnosis of asthma is confirmed.

Unfortunately, children before 6 to eight years of age have difficulty doing this test. Furthermore, if it is done when he is well, the increase in airflow may not be enough to confirm the diagnosis. Therefore, one can conclude that he doesn’t have asthma, and the treatment is wrong.

I believe we don’t have sensitive and reliable tests for children with asthma. The claim of asthma being over-diagnosed is wrong. Some specialists who based their diagnosis only on lung function test when they see the child missed all the other times when the child was sick, when the family doctor had to take care of him.

Until scientists can design a more reliable test, doctors have to use all their clinical skills: get detail history over months and years, check for signs of asthma with careful examination, and use appropriate medications that are effective for asthma. Regular follow up is important to make sure asthma is under good control.

Because your son has improved after using his puffers, it is most important that you work closely with your doctor and continue his treatment. Tests are unlikely to be helpful to confirm the diagnosis. Sometimes, allergy tests can help to identify things around him that he is sensitive to. You can work with your doctor to reduce these triggers. Some children need maintenance treatment with asthma medicine, even daily, to keep them healthy.

Not too many years ago, children and adults were dying regularly from asthma.We don’t hear these as often because we have effective treatment. It would be a shame to see asthmatics die because parents are scared by claims of over-diagnosis and over-treatment.