Background: Few prospective studies have examined the health risks associated with use of snuff and chewing tobacco.
Methods: We studied the association between the use of spit tobacco (snuff or chewing tobacco) and mortality among men enrolled in Cancer Prevention Study I (CPS-I) in 1959 or Cancer Prevention Study II (CPS-II) in 1982. Analyses were based on men who reported exclusive use of snuff or chewing tobacco (7745 in CPS-I, 3327 in CPS-II) or no previous use of any tobacco product (69,662 in CPS-I, 111,482 in CPS-II) at baseline. Twelve-year follow-up of CPS-I, and 18-year follow-up of CPS-II identified 11,871 and 19,588 deaths, respectively. Cox proportional hazards models were used to control for age and other covariates.
Results: Men who currently used snuff or chewing tobacco at baseline had higher death rates from all causes than men who did not in both CPS-I (hazard ratio [HR]=1.17, 95% CI=1.11-1.23) and CPS-II (HR=1.18, 95% CI=1.08-1.29). In CPS-I, current use of spit tobacco was statistically significantly associated with death from coronary heart disease (CHD), stroke, and diseases of the respiratory, digestive, and genitourinary systems, but not with death from cancer. In CPS-II, use of these products was significantly associated with death from CHD, stroke, all cancers combined, lung cancer, and cirrhosis. The associations with cardiovascular and other non-malignant endpoints were attenuated, but not eliminated, by controlling for measured covariates. Former use of spit tobacco was not associated with any endpoint in CPS-II. No clear dose response was observed with either the frequency or duration of usage for any endpoint.
Conclusions: These two prospective studies provide limited evidence that current use of chewing tobacco or snuff may increase mortality from heart disease and stroke.