Smoking Status and Long-Term Survival After First Acute Myocardial Infarction: A Population-Based Cohort Study

Abstract

We compared long-term survival after acute myocardial infarction (AMI) of never-smokers, pre-AMI quitters, post-AMI quitters, and persistent smokers and assessed whether cigarette reduction among persistent smokers is associated with lower mortality. Quitting smoking has been shown to improve outcome after AMI. However, longitudinal cohort data with repeated assessments of smoking and information on multiple confounders are lacking. Moreover, little is known about the importance, if any, of reductions in the amount smoked. Consecutive patients < or = 65 years of age, discharged from 8 hospitals in central Israel after first AMI in 1992 to 1993, were followed through 2005. Extensive data, including self-reported smoking habits, were obtained at baseline and 4 times during follow-up. Cox proportional hazards regressions were used to assess the hazard ratios (HRs) for death associated with smoking categories modeled as time-dependent variables. At baseline, smokers were younger, more likely to be male, and had a lower prevalence of hypertension and diabetes than nonsmokers. Over a median follow-up of 13.2 years, 427 deaths occurred in 1,521 patients. The multivariable-adjusted HRs for mortality were 0.57 (95% confidence interval [CI]: 0.43 to 0.76) for never-smokers, 0.50 (95% CI: 0.36 to 0.68) for pre-AMI quitters, and 0.63 (95% CI: 0.48 to 0.82) for post-AMI quitters, compared with persistent smokers. Among persistent smokers, upon multivariable adjustment including pre-AMI intensity, each reduction of 5 cigarettes smoked daily after AMI was associated with an 18% decline in mortality risk (p < 0.001). Smoking cessation either before or after AMI is associated with improved survival. Among persistent smokers, reducing intensity after AMI appears to be beneficial.