Long-term use of Swedish moist snuff and the risk of myocardial infarction amongst men
ABSTRACT The scientific evidence on cardiovascular risks associated with long-term use of snuff is limited and inconclusive. The use of this smokeless tobacco has increased in recent decades, and adverse health effects associated with snuff use could be of great public health concern.
We aimed to study whether long-term use of snuff affects the risk of myocardial infarction.
Between 1978 and 1993 all construction workers in Sweden were offered repeated health check-ups by the Swedish Construction Industry's Organization for Working Environment Safety and Health. A cohort was created with information on tobacco use and other risk factors, collected through questionnaires.
In total, 118,395 nonsmoking men without a history of myocardial infarction were followed through 2004. Information on myocardial infarction morbidity and mortality was obtained from national registers. Relative risk estimates were derived from Cox proportional hazards regression model, with adjustment for age, body mass index and region of residence.
Almost 30% of the men had used snuff. In total, 118 395 nonsmoking men without a history of myocardial infarction were followed through 2004. The multivariable-adjusted relative risks for ever snuff users were 0.91 (95% confidence interval, 0.81-1.02) for nonfatal cases and 1.28 (95% confidence interval, 1.06-1.55) for fatal cases. Heavy users (>or=50 g day(-1)) had a relative risk of fatal myocardial infarction of 1.96 (95% confidence interval, 1.08-3.58). Snuff use increased the probability of mortality from cardiovascular disease amongst nonfatal myocardial infarction patients.
Our results indicate that snuff use is associated with an increased risk of fatal myocardial infarction.
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ABSTRACT: The accuracy and appropriateness of an analysis often cannot be verified by the contemporary peer review process. Peer review is also unlikely to identify possible publication bias in situ (PBIS) (running many different statistical models but only reporting the results of one, often an outlier result). A review of articles reporting analyses of a cohort of Swedish construction workers revealed unacknowledged and unexplained variations in methodology, including the use of different variables measuring tobacco use, age and body mass index and a failure to adequately and accurately reference previous related articles about the cohort. Seemingly minor changes in methodology, such as the cutoffs used to convert continuous variables to categorical variables may result in significant changes to the results. These inconsistencies were likely not discovered during the peer review process as it would have required that reviewers conduct a systematic review of previous analyses of the dataset. Practical solutions to this dilemma include enhanced post publication review and ensuring that data are available for secondary analysis.