Myocardial Infarction and Sudden Cardiac Death in Olmsted County, Minnesota, Before and After Smoke-Free Workplace Laws
Are rates of myocardial infarction (MI) and sudden cardiac death (SCD) reduced with a smoke-free restaurant ordinance, which was implemented in Olmsted County, Minnesota, and in 2007, all workplaces, including bars, which became smoke free?
Data from the Rochester Epidemiology Project were examined during an 18-month period before and after implementation of each smoke-free ordinance. Olmsted County, located in southeastern Minnesota, has a population of 144,248 (86% white, 51% female). Only a few providers (chiefly Mayo Clinic and Olmsted Medical Center) deliver nearly all medical care to county residents. Medical records used by each provider capture information for all encounters and can be retrieved from indices based on all diagnoses and procedures maintained by Mayo Clinic. In Olmsted County, a smoke-free restaurant law that did not include bars or other workplaces (Ordinance 1) was implemented on January 1, 2002, and on October 1, 2007, all workplaces (including bars) became smoke free (Ordinance 2). The primary outcomes of interest were MI and SCD. All MIs were continuously abstracted and validated, using rigorous standardized criteria relying on biomarkers, cardiac pain, and Minnesota coding of the electrocardiogram. SCD was defined as out-of-hospital deaths associated with coronary disease.
During the 18 months before and after implementation of each smoke-free ordinance, there were 717 incident cases of MI, and 514 people experienced SCD. Demographic and clinical characteristics of the patients were not significantly different before and after ordinance periods, except for hyperlipidemia in persons experiencing SCD before and after Ordinance 1 (36.4% vs. 54.0%, respectively; p = 0.004). Comparing the 18 months before implementation of the smoke-free restaurant ordinance with the 18 months after implementation of the smoke-free workplace law, the incidence of MI declined by 33% (p < 0.001), from 150.8 to 100.7 per 100,000 population, and the incidence of sudden cardiac death declined by 17% (p = 0.13), from 109.1 to 92.0 per 100,000 population. During the same period, the prevalence of smoking declined; however, the prevalence of hypertension, diabetes mellitus, hypercholesterolemia, and obesity either remained constant or increased.
The investigators concluded that a substantial decline in the incidence of MI was observed after smoke-free laws were implemented, the magnitude of which is not explained by community co-interventions or changes in cardiovascular risk factors, with the exception of smoking prevalence.
These data provide strong evidence for the cardiovascular benefits of smoking bans. Further data on other outcomes such as stroke would be of interest as well.
Keywords: Myocardial Infarction, Biological Markers, Minnesota, Death, Sudden, Cardiac, Smoking
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