Smoking is a major risk factor for heart disease. Over the past decade, the prevalence of smoking and the number of cigarettes smoked per day have decreased in Canada. Using a contemporary cohort of Canadian men and women, this study measured associations between smoking, smoking cessation and heart disease.
The study is based on nine cycles of data (1994/1995 through 2010/2011) from the National Population Health Survey, which collected information on smoking status every two years. The study sample consists of 4,712 men and 5,715 women aged 25 or older and free from heart disease in 1994/1995. Heart disease was determined by self-report of diagnosis, medication for, or death from heart disease. Relative risks of incident heart disease were compared among current daily smokers, former daily smokers, and those who never smoked daily.
Compared with those who had never smoked daily, current daily smokers had a 60% higher risk of incident heart disease during the follow-up period. The risks were lower among current daily smokers who consumed fewer cigarettes. Although smoking cessation was associated with a lower risk of heart disease, 20 or more years of continuous cessation were required for the risk to approach that of people who never smoked daily.
Smoking cessation and cutting down the number of cigarettes smoked per day reduce the risk of heart disease.
Cohort study, longitudinal studies, relative risks
Heart disease is the second-leading cause of death in Canada, accounting for just over 20% of all deaths in 2009. Thirty years ago, the U.S. Surgeon General’s Report on The Health Consequences of Smoking: Cardiovascular Disease concluded that smoking is causally related to coronary heart disease for both men and women. [Full Text]
Margot Shields and Kathryn Wilkins were formerly with the Health Analysis Division at Statistics Canada.
What is already known on this subject?
- Heart disease is the second-leading cause of death in Canada, accounting for just over 20% of all deaths in 2009.
- Smoking is causally related to coronary heart disease for both men and women.
- Over the past decade, the prevalence of smoking has declined in Canada, as have smoking intensity levels among current daily smokers.
- Smoking cessation reduces the risk of heart disease, but the number of years of cessation required for the risk for former smokers to decline to the level for those who never smoked is uncertain.
What does this study add?
- Based on a contemporary cohort of the Canadian population followed from 1994/1995 to 2010/2011, the risk of incident heart disease was 60% higher among current daily smokers than among people who never smoked daily.
- Although smoking cessation was associated with a decreased risk of incident heart disease, 20 continuous years of cessation were needed for the risk of heart disease for former daily smokers to approach that for people who never smoked daily.
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