Smoking may be linked to more diseases – and more deaths – than previously estimated, according to a new study led by American Cancer Society researchers, published online in the New England Journal of Medicine February 11.
The study concludes that the current estimate of the number of deaths caused by cigarette smoking each year – 480,000 in the 2014 Surgeon General’s report – may in fact be too low. The Surgeon General’s estimate includes deaths from the 21 diseases that research has already established are caused by smoking. These are: 12 types of cancer, 6 categories of cardiovascular disease, diabetes, chronic obstructive pulmonary disease [COPD], and pneumonia including influenza.
The new study finds that there are a number of other diseases that may also be increasing death rates among smokers. This is based on an analysis of data from 421,378 men and 532,651 women followed from 2000 to 2011. During that time period, there were 181,377 deaths, 16,475 of which were among current smokers. In order to get a large enough number of participants, the authors combined data from 5 different studies: the American Cancer Society Cancer Prevention Study II Nutrition Cohort, the Nurses’ Health Study I cohort, the Health Professionals Follow-up Study cohort, the Women’s Health Initiative cohort, and the National Institutes of Health – AARP Diet and Health Study cohort.
The authors found that 17% of the increased risk of death among smokers was due to causes that are not currently attributed to smoking. Their analysis uncovered a total of 14 causes of death associated with smoking that were not previously established as caused by smoking.
“In particular, smoking was associated with at least a doubling of risk of death from several causes,” which include kidney failure, reduced blood flow to the intestines, high blood pressure, infections, and various respiratory diseases other than COPD, the study states. The authors also assessed deaths among former smokers and found that the excess risk of dying from each of these causes declined as the number of years since quitting increased.
Brian Carter, M.P.H, the lead author on the study and an epidemiologist at the American Cancer Society sees the findings as significant. “In our study, smokers had higher death rates from many diseases not currently established as caused by smoking, and we think there is strong evidence that smoking is likely to cause some of these diseases. If our results hold true for the U.S. as a whole, about 60,000 more Americans than we thought may be killed each year by cigarette smoking,” says Carter. “For perspective, this additional number of deaths outnumbers deaths from motor vehicle accidents, influenza, or liver cirrhosis,” Carter adds.
Carter says that the findings highlight the importance of accelerating tobacco control efforts.
The authors do note that more research is still needed to further verify their results and determine the specific biological processes linking smoking to these causes of death.
FOR MEDIA: For more information about this study, please see the press release.