Discontinuation of smokeless tobacco and mortality risk after myocardial infarction

Abstract

Background: 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.

Methods and results: 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).

Conclusions: 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.

Keywords: mortality; myocardial infarction; prognosis; risk factors; smokeless tobacco.