Quitting Smoking Leads to Significant Reduction in Mortality Risks After 5 Years

Women smokers who quit reduce the risk of death from heart disease within 5 years, and their risk of any other smoking-related death by 20%, according to a recent study.

"Tobacco use remains the leading preventable cause of death in the United States. Globally, approximately 5 million premature deaths were attributable to smoking in 2000. The World Health Organization projects by 2030 that tobacco-attributable deaths will annually account for 3 million deaths in industrialized countries and 7 million in developing countries," the authors write. They add that the rate of mortality risk reduction after quitting compared with continuing to smoke is uncertain.

By analyzing data from the Nurses’ Health Study, an observational study of 104,519 female participants, with follow-up from 1980 to 2004, Stacey A. Kenfield, Sc.D., of the Harvard School of Public Health, Boston and his colleagues measured the relationship between cigarette smoking and quitting smoking on mortality in women. 12,483 deaths were recorded in this group, of which 4,485 (35.9%) had never smoked, 3,602 (28.9%) were current smokers, and 4,396 (35.2%) were among past smokers.

A 13% risk reduction in mortality from any cause within the first 5 years of stopping smoking (compared with continuing to smoke), with the excess risk falling to the level of someone who had never smoked 20 years after quitting.

According to the study, "Significant trends were observed with increasing years since quitting for all major cause-specific outcomes. A more rapid decline in risk after quitting smoking compared with continuing to smoke was observed in the first 5 years for vascular diseases compared with other causes."

In regard to coronary heart disease, 61% of the full benefit of quitting was realized within the first 5 years; similarly for cerebrovascular mortality where 42% of the potential benefit was realized within the first 5 years after quitting. Death due to respiratory disease showed an 18% reduction in risk within 5 to 10 years of quitting.

Lung cancer mortality showed a 21% risk reduction during the first 5 years compared with people who did not quit, but the excess risk remained for 30 years. Past smokers with 20 to less than 30 years of not smoking showed an 87% reduction in risk of lung cancer mortality compared with continuing smokers. The researchers also found that approximately 64 percent of deaths among current smokers and 28 percent of deaths among former smokers were attributable to cigarette smoking.

"Early age at initiation is associated with an increased mortality risk so implementing and maintaining school tobacco prevention programs, in addition to enforcing youth access laws, are key preventive strategies. Effectively communicating risks to smokers and helping them quit successfully should be an integral part of public health programs," the authors conclude.

Source: Journal of the American Medical Association (JAMA), April 7, 2008 – 2008;299[17]:2037-2047

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