May 6, 2008 -- The risk of dying from smoking-related causes drops significantly within just a
few years of giving up cigarettes, even for longtime smokers, new research
Within five years of quitting smoking, study participants experienced a 13%
reduction in the risk of death from all causes, a 47% risk reduction in
heart disease-related deaths, and a 27% reduction in the risk of death from
Within 20 years of quitting, the risk of dying among former smokers was
similar to that of lifetime nonsmokers for most causes of death, with the
The findings suggest that it is never too late to derive health benefits
from giving up smoking, says researcher Stacey A. Kenfield, ScD, of the Harvard
School of Public Health.
The study appears in the May 7 issue of The Journal of the American
"The most dramatic decreases in mortality were seen within the first five
years for many diseases and the risk kept declining over time," Kenfield tells
The study included about 105,000 American women participating in the ongoing
Nurses Health Study.
The women were between the ages of 30 and 55 at enrollment in 1976.
Surviving participants completed detailed health questionnaires every two years
for the past three decades.
Between the years 1980 and 2004,12,483 of the women died, with 36% of deaths
occurring among women who had never smoked, 29% occurring among current
smokers, and 35% occurring among past smokers.
The women in the study who gave up cigarettes smoked for an average of 15
years. Among the major findings from the study:
64% of deaths in current smokers and 28% of deaths in former smokers were
attributable to smoking.
The risk of dying from heart disease dropped rapidly within five years of
stopping smoking and equalized to that of a never-smoker within 20 years of
With the exception of lung cancer, the risk of dying from respiratory
disease fell to that of a lifetime nonsmoker within 20 years.
The risk of dying from lung cancer dropped by 21% within five years of
quitting, but the excess risk did not disappear for a full three decades.
The relationship between the number of cigarettes smoked per day and risk
of death varied by disease process. The relationship was weaker for vascular
disease, suggesting that "the first few cigarettes account for most of the
increased risk," whereas the correlation was stronger for death due to
respiratory disease, suggesting that the absolute amount smoked is more
critical for these disorders.
Early smokers were most at risk of dying from smoking-related causes.
Current smokers who started at age 17 or younger had a significantly higher
risk of dying than smokers who took up the habit after age 25. This was
especially true for respiratory disease, lung cancer, and other smoking-related