Asthma Diagnosis Later Reversed in About 1 in 3 Adults, Study Finds

— -- Although asthma is considered a chronic disease, doctors have been puzzled by its often changing nature that can makes prescribing medicine, or stopping them, tricky.

A study published today in the Journal of the American Medical Association (JAMA) found that about one-third of adults tested for the study, who had been diagnosed with asthma in the previous five years, showed no evidence of the condition during later follow-up examinations and testing.

"We see a lot of people who were told they have asthma and we can't confirm it," Dr. Richard Lockey, the director of Allergy and Immunology at the University of South Florida College of Medicine, who was not involved in the study, told ABC News.

The reverse can also be true, he said; a person can test negative for asthma after the most sophisticated tests and still exhibit symptoms two years later.

He said the variation in the disease makes him wary to declare someone asthma-free if they have had symptoms in the past and were diagnosed.

"It's a very, very complicated disease," Lockey said.

This study in part aimed to limit exposure to asthma medications for adults who many no longer need it. The 613 participants were given multiple tests and examinations to determine if they had signs of asthma. Researchers from multiple institutions, including the University of Manitoba and the University of Ottawa, determined that 203 participants, or approximately 33 percent, did not have baseline symptoms of asthma after the initial examination. During a 15-month follow-up six participants ended up exhibiting signs of asthma and again returned to their asthma medication.

Some limitations of the research included the time interval studied and other medical conditions participants may have had. "Participants in whom current asthma was ruled out were followed for up to 15 months, but it is possible that some patients in remission, such as those with intermittent asthma provoked by specific allergens, could experience subsequent recurrence of asthma beyond a 15-month follow-up period. The sensitivity of bronchial challenge tests to detect asthma is 98% but not 100%," the study said. The test can also be falsely positive in patients with allergies or smokers.

Asthma can be a tricky disease to diagnose since other conditions, such as acid reflux and vocal cord dysfunction syndrome, can mimic the symptoms of asthma.

Dr. Todd Rambasek, an associate professor at the Ohio College of Osteopathic Medicine and fellow for the American Academy of Allergy, Asthma & Immunology, said some people are diagnosed at primary care physician's office, who may mistake similar conditions for asthma.

"It's not surprising ... people are often over treated with asthma medication," said Rambasek, explaining taking extra asthma medication will not cause as severe side effects as other common medication such as blood pressure medication or diabetic medication.

Additionally he said a person's asthma symptoms and severity can change over time. Ramasek said some medical studies have shown people with a childhood diagnosis of asthma usually have diminished symptoms as adults.

"It's a dynamic thing, it varies and comes and goes," Rambasek said of asthma.