Background: Although several epidemiological studies have examined the mortality among users of spit tobacco, none have compared mortality of former cigarette smokers who substitute spit tobacco for cigarette smoking (“switchers”) and smokers who quit using tobacco entirely.
Methods: A cohort of 116 395 men were identified as switchers (n = 4443) or cigarette smokers who quit using tobacco entirely (n = 111 952) when enrolled in the ongoing US American Cancer Society Cancer Prevention Study II. From 1982 to 31 December 2002, 44 374 of these men died. The mortality hazard ratios (HR) of tobacco-related diseases, including lung cancer, coronary heart disease, stroke and chronic obstructive pulmonary disease, were estimated using Cox proportional hazards regression modelling adjusted for age and other demographic variables, as well as variables associated with smoking history, including number of years smoked, number of cigarettes smoked and age at quitting.
Results: After 20 years of follow-up, switchers had a higher rate of death from any cause (HR 1.08, 95% confidence interval (CI) 1.01 to 1.15), lung cancer (HR 1.46, 95% CI 1.24 to 1.73), coronary heart disease (HR 1.13, 95% CI 1.00 to 1.29) and stroke (HR 1.24, 95% CI 1.01 to 1.53) than those who quit using tobacco entirely.
Conclusion: The risks of dying from major tobacco-related diseases were higher among former cigarette smokers who switched to spit tobacco after they stopped smoking than among those who quit using tobacco entirely.
- CPS-II, Cancer Prevention Study II
- NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone
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Funding: The Cancer Prevention Study II cohort is supported by the American Cancer Society. This publication was supported in part by Grant/Cooperative Agreement Number U50/CCU424071-02 from the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of Centers for Disease Control and Prevention.
Competing interests: None declared.
Contributors: Staff of the Epidemiology and Surveillance Research Department of the American Cancer Society designed and conducted the study, including collection, analysis, interpretation and presentation of the manuscript; no staff at the American Cancer Society, other than study investigators, reviewed or approved the manuscript. Staff at the Office of Smoking and Health at the Centers for Disease Control and Prevention contributed to the study design, interpretation and presentation; the Centers for Disease Control and Prevention reviewed and approved this manuscript before submission.
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