Many adults today who have been diagnosed with asthma many not actually have the condition, a new Canadian study warns.

Using objective tests, the researchers found that one-third of over 600 adults diagnosed with asthma did not have the disease, and 35 percent of them were medicating every day. This group kept testing negative for asthma after multiple retests, showing no signs of worsening symptoms when they stopped medication.

In some cases, according to lead researcher and respiratory expert Dr. Shawn Aaron of Ottawa Hospital, some of the participants had the obvious signs of the condition during diagnosis period, but their symptoms later went into remission. In most cases, however, it is unknown whether the asthma went away on its own or the patients were misdiagnosed at the beginning.

No Asthma In One-Third Of Subjects

The team studied over 600 adults living in 10 Canadian cities and had been diagnosed with asthma in the last five years.

The subjects underwent spirometry, and if they tested negative, they proceeded to a second test where they inhaled methacholine, a common asthma trigger. If they still tested negative, they would be told to lower their medication dose, stop taking the drugs altogether, and then go through a fourth and final test if still appearing negative.

Thirty-three percent or around 200 of the subjects did not have asthma, as they have negative results on the diagnostics.

The team followed the 200 participants for another year and discovered that over 90 percent still showed no signs of the condition despite quitting their medications. When evaluated by study doctors, around 60 percent were found to have seasonal allergies, acid reflux, or a breathing issue due to obesity.

Lack Of Objective Testing?

Aaron warned about asthma diagnoses without actual objective testing, with nearly half diagnosed based only on signs and the doctor’s evaluation.

“[A doctor] would order a test of the patient’s blood sugar levels [to diagnose diabetes],” he said as an example.

A spirometer, a device that gauges how much air someone can blow out of her lungs and how quickly, is often used to diagnose the disease. Aaron speculated that there are doctors who may not be comfortable using it and may find that they lack the time or expertise to perform it.

Dr. Richard Lockey of University of South Florida told ABC News that because asthma is a highly complicated disease, it makes him wary of declaring someone asthma-free if they exhibited symptoms in the past and were already diagnosed.

Dr. Todd Rambasek of the Ohio College of Osteopathic Medicine said the overtreatment of asthma is no longer surprising, although adding that taking extra asthma drugs will not cause as severe adverse effects as other common medications for diabetes or blood pressure.

"[Asthma is] a dynamic thing, it varies and comes and goes," he said.

The team clarified, though, that some asthma patients may undergo long remission periods before recurrence, meaning asthma could still return after the study ended.

The findings were discussed in the journal Journal of the American Medical Association.