A new Special Article published in the New England Journal of Medicine (NEJM) says that mortality among current smokers is still two to three times greater than among persons who never smoked. Moreover, the paper’s coauthors find that higher mortality among smokers is most likely attributable to considerably more than the 21 common diseases for which cigarette smoking, the leading preventable cause of death worldwide, has been formally established as a cause.

These officially recognized smoking-related diseases, some examples being 12 types of cancer, stroke, coronary heart disease and chronic obstructive pulmonary disease (COPD), get included in official U.S. smoking-related mortality estimates by the Surgeon General’s office, such as that some 480,000 people in the US die from smoking related causes, and that smoking officially costs the US economy roughly $289 billion annually, representing some $96 billion in health care costs and more than $156 billion is lost productivity.

However, if as suspected smoking is also a factor in causing diseases additional to the official 21 currently associated, these estimates, sobering as they are, may actually be significantly underestimating the number of deaths attributable to smoking by about 17 percent. Examples of diseases no currently included in smoking mortality estimates are intestinal ischemia, kidney failure, various infections, hypertensive heart disease and assorted respiratory disorders outside that don’t come under the COPD classification.

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The article, entitled “Smoking and Mortality Beyond Established Causes,” (N Engl J Med 2015; 372:631-640February 12, 2015DOI: 10.1056/NEJMsa1407211) is coauthored by Brian D. Carter, M.P.H.; Christian C. Abnet, Ph.D.; Diane Feskanich, Sc.D.; Neal D. Freedman, Ph.D.; Patricia Hartge, Sc.D.; Cora E. Lewis, M.D.; Judith K. Ockene, Ph.D.; Ross L. Prentice, Ph.D.; Frank E. Speizer, M.D.; Michael J. Thun, M.D.; and Eric J. Jacobs, Ph.D.

Lead author Dr. Eric Jacobs is Strategic Director of Pharmacoepidemiology for the American Cancer Society (ACS), which funded the study. The researchers conclude that a substantial proportion of excess mortality among current smokers between 2000 and 2011 was related to associations with diseases for which smoking has not been formally established as a cause. The coauthors recommend that these suspected associations be investigated further and, if it can be proved appropriate, that they be included when smoking mortality burden a part of investigations.

This new study adds to and amplifies findings of two previous studies published by the NEJM in 2013 that identified smoking as still a huge public health problem in the United States, but also found that smokers who quit the habit between the ages of 25 and 34 regain nearly the same life expectancy as persons who have never smoked.

Unhappily, the 2013 studies also found that despite the enormous health benefits of quitting and surveys finding that about 70 percent of smokers want to quit, the sad reality is that only a small percentage actually succeed in doing so annually.

One of the 2013 studies, entitled 21st-Century Hazards of Smoking and Benefits of Cessation in the United States was coauthored by
Prabhat Jha, M.D.; Chinthanie Ramasundarahettige, M.Sc., Victoria Landsman, Ph.D., Brian Rostron, Ph.D.; Michael Thun, M.D.; Robert N. Anderson, Ph.D.; Tim McAfee, M.D.; and Richard Peto, F.R.S. (N Engl J Med 2013; 368:341-350January 24, 2013DOI: 10.1056/NEJMsa1211128), who note that extrapolation from 1980s era studies suggests that smoking causes 25% of deaths among women and men 35 to 69 years of age in the United States and reduces an individual’s life expectancy by at least 10 years, but that smokers can significantly extend their life expectancy by quitting.

The research indicated that smokers who quit at 25 to 34 years of age had survival curves nearly identical to those for study subjects who had never smoked, adding some 10 years to their projected lifespans compared with persons who continued to smoke. Persons quitting at 35 to 44 years of age could expect to gain about 9 years of life, as compared with those who continued smoking. Smokers who stopped smoking at 45 to 54 years of age and those who stopped at 55 to 64 years of age gained about 6 and 4 years of life expectance respectively, The researchers estimate overall mortality among smokers of both sexes in the United States to be about three times greater than that among otherwise similar persons who never smoked, and that smokers lose, on average, at least a decade of life.

The researchers further note that between 1965 to 2010, cigarette smoking prevalence of among adults in the United States decreased from 42 percent to 19 percent, thanks largely to increased cessation rates. However, they found that the United States has about 35 million current or future smokers under 35 years of age, and that prevalence of smoking had changed little from 2004 to 2010.

Overall, they conclude that their findings, as well as those from other studies, highlight the worldwide importance of tobacco control, noting that most of the world’s estimated 1.3 billion smokers live in low- and middle-income countries, and that worldwide, about 30 million young adults begin smoking annually with current patterns of behavior suggesting that most will not stop.

They suggest that options to help increase cessation rates and decrease initiation rates worldwide might include higher cigarette prices through increased excise taxes, more restrictions on smoking in public places, tobacco advertising and promotion bans, more public education about smoking hazards and cessation benefits of, and easy access to cessation support.

The second 2013 study, entitled “50-Year Trends in Smoking-Related Mortality in the United States“ is coauthored by Michael J. Thun, M.D.; Brian D. Carter, M.P.H.; Diane Feskanich, Sc.D.; Neal D. Freedman, Ph.D., M.P.H.; Ross Prentice, Ph.D.; Alan D. Lopez, Ph.D.; Patricia Hartge, Sc.D.; and Susan M. Gapstur, Ph.D., M.P.H. (N Engl J Med 2013; 368:351-364January 24, 2013DOI: 10.1056/NEJMsa1211127), who found that death rates among female smokers previously documented to be lower than those among male smokers had actually increased and converged with those of men for lung cancer, chronic obstructive pulmonary disease (COPD) and other tobacco-related diseases. The researchers attributed this increase in large part to a convergence in smoking patterns among men and women since the 1960s, with women starting to smoke earlier in adolescence and until recently smoking more cigarettes per day, and commenting that this finding confirms a prediction that “women who smoke like men die like men.”

The study also notes that women have more difficulty quitting smoking than men, and consequently for both current and former female smokers, the number of years of smoking has increased. The researchers also note that female smokers today are less educated and less affluent than were female smokers of 20 to 40 years ago, and that while mortality risk from lung cancer among male smokers appears to have stabilized since the 1980s, it continues to increase among female smokers. They found that for men 55 to 74 years of age and women 60 to 74 years of age, mortality rates from all causes combined are now at least three times as high among current smokers as among persons who’ve never smoked, and that several studies show more than two thirds of all deaths among current smokers in those age groups associated with smoking.

The study also observes that chronic obstructive pulmonary disease (COPD) mortality continues to increase among both male and female smokers in contrast to a significant decrease in risk among men who never smoked. The researchers say their analyses of data from former smokers confirm that quitting smoking at any age dramatically lowers mortality from all major smoking-related diseases, noting: “A plausible explanation for the continuing increase in deaths from COPD among male smokers is that cigarettes marketed since the late 1950s have undergone design changes that promote deeper inhalation of smoke.”

The researchers note that cigarette design changes may also have contributed to an increase in one form of lung cancer (called peripheral adenocarcinomas) thereby offsetting declines in other forms of lung cancer.

The Campaign for Tobacco-Free Kids says these studies’ findings underscore why the Food and Drug Administration must aggressively exercise its authority over tobacco products, including the authority to stop tobacco industry manipulation that harms public health, and that while the U.S. has made significant progress in reducing smoking, these studies remind us that there is still much work to do to win the campaign whose end-game is to eliminate the nation’s number one cause of preventable death.

Sources:
The New England Journal of Medicine (NEJM)
The American Cancer Society (ACS)
Campaign for Tobacco-Free Kids

Image Credit:
The American Cancer Society (ACS)