Discontinuation of smokeless tobacco and mortality risk after myocardial infarction.

Abstract

Given the indications of increased risk for fatal myocardial infarction (MI) in people who use snus, a moist smokeless tobacco product, we hypothesized that discontinuation of snus use after an MI would reduce mortality risk. All patients who were admitted to coronary care units for an MI in Sweden between 2005 and 2009 and were <75 years of age underwent a structured examination 2 months after discharge (the baseline of the present study). We investigated the risk of mortality in post-MI snus quitters (n=675) relative to post-MI continuing snus users (n=1799) using Cox proportional hazards analyses. During follow-up (mean 2.1 years), 83 participants died. The mortality rate was 9.7 (95% confidence interval, 5.7-16.3) per 1000 person-years at risk in post-MI snus quitters and 18.7 (14.8-23.6) per 1000 person-years at risk in post-MI continuing snus users. After adjustment for age and sex, post-MI snus quitters had half the mortality risk of post-MI continuing snus users (hazard ratio, 0.51; 95% confidence interval, 0.29-0.91). In a multivariable-adjusted model, the hazard ratio was 0.57 (95% confidence interval, 0.32-1.02). The corresponding estimate for people who quit smoking after MI versus post-MI continuing smokers was 0.54 (95% confidence interval, 0.42-0.69). In this study, discontinuation of snus use after an MI was associated with a nearly halved mortality risk, similar to the benefit associated with smoking cessation. These observations suggest that the use of snus after MI should be discouraged.