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Asthma is a chronic lung disease that affects an estimated three million Canadians. (Associated Press)

Anyone with asthma has a high likelihood of having the chronic lung disease for life, a new Canadian study suggests.

The study of more than 613,394 people identified as having asthma in 1993, and tracked over 15 years, found that most were dealing with the lung problem most of the time, although that was interspersed with periods when the condition seemed to be in remission and they weren't getting medical help.

In fact, of the 613,394 individuals, 504,851 (82.3 per cent) had active asthma during the 15-year followup.

"A lot of people have asthma and would like to know how their disease will affect them over time," study lead author Andrea Gershon, an ICES scientist and respirologist who also works at Toronto's Sunnybrook Health Sciences Centre, says in a 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, from the Institute for Clinical Evaluative Sciences (ICES) in Toronto, was published in Tuesday's Journal of Allergy and Clinical Immunology.

Asthma especially a problem among young, elderly

Other findings include:

  • About three-quarters of study subjects with active asthma had gaps of time, often lasting years, when their asthma appeared inactive and they were likely in remission.
  • People with a history of medical visits for asthma, children and people over 65 years, and those also diagnosed with chronic obstructive pulmonary disease (COPD) were found to have more active asthma.

Potential asthma triggers include:

  • Mould.
  • Animal dander.
  • Pollen.
  • Cockroaches.
  • Dust mites.
  • Certain drugs (ASA, beta blockers).
  • Chemicals, fumes and odours.
  • Respiratory viral infections.
  • Cold air, thunderstorms.
  • Strenuous physical exercise.
  • Tobacco smoke.
  • Air pollution.

 

Asthma is a chronic inflammatory disease of the airway that causes symptoms including shortness of breath, tightness in the chest, coughing and wheezing.

An estimated three million Canadians have asthma, and its prevalence has been increasing over the last 20 years, according to the Asthma Society of Canada.

Although its cause isn't precisely known, the strongest risk factors include having a family history of the condition, being exposed in infancy to high levels of antigens such as house dust mites, and exposure to tobacco smoke or chemicals in the workplace, the society says.

Canadian asthma management guidelines focus on avoiding triggers, long-term medication such as anti-inflammatories that are used to reduce airway inflammation and prevent symptoms, and quick-relief (rescue) medicines including inhalers.

Gershon says knowing you have asthma for life will help to manage the condition over the long term.

The study notes its findings echo previous research by other scientists that also suggests people diagnosed with asthma will continue to have it indefinitely.

ICES is an independent, non-profit organization that uses population-based health information to study a range of health-care issues.