Smokeless tobacco as a possible risk factor for stroke in men: a nested case-control study.

BACKGROUND AND PURPOSE Snuff and other forms of smokeless tobacco are widely used in some populations. Whereas the detrimental cardiovascular effects of smoking are well documented, possible health hazards associated with the use of smokeless tobacco remain controversial. The purpose of this study was to explore whether the use of snuff, a smokeless tobacco product, increases the risk of stroke in men. METHODS In a nested case-control study (1 case and 2 matched controls without cardiovascular disease), information on tobacco habits was collected through population risk factor surveys. During follow-up, first-ever fatal and nonfatal strokes occurring among 25- to 74-year-old participants were identified in a population-based stroke register. The study was restricted to men (276 cases, 551 controls). RESULTS The unadjusted odds ratio for stroke in regular cigarette smokers compared with men who never used tobacco was 2.21 (95% CI, 1.29 to 3.79). When never-smoking regular snuff dippers (excluding ex-smokers) were compared with men who never used tobacco, the unadjusted odds ratio was 1.05 (95% CI, 0.37 to 2.94). The odds ratio for never-snuffing smokers versus never-smoking snuff users was 2.90 (95% CI, 0.92 to 9.1). After adjustment for multiple cardiovascular risk factors, the odds ratio for having a stroke was 1.74 (95% CI, 0.85 to 3.54) in regular smokers and 0.87 (95% CI, 0.41 to 1.83) in regular snuff users. CONCLUSIONS Whereas regular smoking doubles the risk of stroke in men, snuff use is not associated with any apparent excess risk. Chemical moieties produced by burning tobacco are probably the most important contributors to smokers' excess risk of atherothrombotic disease, including stroke.