Tobacco-related disease mortality among men who switched from cigarettes to spit tobacco.

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.