The study tracked almost 614,000 province of Ontario residents who were identified as having asthma in 1993, following them for 15 years.

While some patients reported periods of disease inactivity, sometimes for years, most were managing their asthma most of the time. In the 15-year followup, 82.3 percent had active asthma.

“A lot of people have asthma and would like to know how their disease will affect them over time,” study lead author Dr. Andrea Gershon, a respirologist, said in a media release.

“These findings offer insight into the course of asthma activity and support the hypothesis that once a person has asthma, they will continue to have it for life.”

The study was conducted by researchers for the Institute for Clinical Evaluative Sciences (ICES) in Toronto, and was published in the Journal of Allergy and Clinical Immunology.