Both men and women who smoke are three times as likely to die as those who don’t.
Two large population-based studies have come to the same conclusion: Smokers are almost certainly going to die years and years sooner than nonsmokers.
"This analysis showed that a person who had never smoked was about twice as likely as a current smoker to reach 80 years of age," Dr. Prabhat Jha and his associates reported in the Jan. 24 issue of the New England Journal of Medicine (N. Engl. J. Med. 2013:368:341-50). "Among current smokers, survival was shorter by about 11 years for women and by about 12 years for men, as compared with participants who had never smoked."
The report wasn’t all bad news, however. Kicking the habit at any time added years of life, said Dr. Jha of the Center for Global Health Research, Toronto, and his coauthors.
The investigators examined smoking and smoking cessation among 113,752 women and 88,496 men who participated in the U.S. National Health Interview Survey from 1997 to 2004. These data were then correlated to information in the National Death Index up until the end of 2006.
The investigators then calculated the probability of survival in each group from 25 to 79 years of age. The mean follow-up was 7 years, with 10,743 deaths occurring in that age range.
After adjusting for education, alcohol use, and adiposity, men and women who smoked were three times more likely to have died than nonsmokers. The estimated probability of survival to the age of 80 years was 38% among women smokers but 70% for those who had never smoked. For male smokers, the probability of survival to age 80 was 26%, compared with 61% for those who had never smoked.
Both women and men who smoked were significantly more likely than nonsmokers to die in all of the smoking-related conditions examined:
• Lung cancer (hazard ratios of 18 and 15 for women and men, respectively).
• Other cancers (HR, 2 and 2).
• All cancers (HR, 3 and 4).
• Ischemic heart disease (HR, 3.5 and 3).
• Stroke (HR, 3 and 2).
• Other vascular disease (HR, 3 and 2).
• Respiratory disease (HR, 8.5 and 9).
• Other unspecified causes (HR, 2 and 2).
• All medical disorders (HR, 3 and 3).
• Accidents (HR, 4 and 2).
"At 25-79 years of age, about 62% of all deaths among female smokers and 60% of all deaths among male smokers would have been avoided if the rates of death from diseases among smokers had been the same as the rates among those who had never smoked," the authors noted.
Quitting smoking, on the other hand, conferred significant survival benefits, no matter when it occurred. Smokers who quit at age 25-34 years had similar survival to that of never-smokers. "Those who quit smoking gained about 10 years of life, as compared with those who continued to smoke."
Quitting at 35-44 years added 9 years of life, the authors found – not quite as good as those who quit earlier, but still a significant gain. "Smokers who had quit by about 39 years of age still had a 20% excess risk as compared with those who had never smoked. Although this hazard is substantial, it is much smaller than the 200% excess risk among those who continued to smoke."
Smokers who stopped at age 45-54 years gained 6 years of life, and those who quit at age 55-64 years about 4 more years of life. "Even cessation at the age of 45 to 54 years reduced the excess risk of death by about two-thirds," according to Dr. Jha and his coauthors.
While the study concluded that quitting at any age is a good idea, it shouldn’t be construed as a license to smoke longer. "That is not to say, however, that it is safe to smoke until 40 years of age and then stop, for the remaining excess risk of about 20% is substantial; it means that about one in six of these former smokers who dies before the age of 80 years would not have died."
The results are consistent with those of other studies around the world, the investigators said. The implications are staggering, especially for lower-income countries where smoking is more common and quitting less common.
"On the basis of current rates of smoking initiation and cessation, smoking, which killed about 100 million people in the 20th century, will kill about 1 billion in the 21st century."