Meta Analysis Studies of Heart Attack Rates

This page presents short descriptions of the findings of meta-analysis studies into the effect of smokefree air laws on heart attack rates. Meta-analysis is a statistical technique for combining results from various individual studies on the same topic.

Jones, M.R.; Barnoya, J.; Stranges, S.; Losonczy, L.; Navas-Acien, A., "Cardiovascular events following smoke-free legislations: an updated systematic review and meta-analysis," Current Environmental Health Reports 1(3): 239-249, September 1, 2014.

This meta-analysis examined results from thirty-one studies into the effect of smokefree legiaslation on coronary events and concluded that, "The implementation of smoke-free legislations was related to reductions in acute coronary event hospitalizations in most populations evaluated. Benefits are greater in locations with comprehensive legislations and with greater reduction in smoking prevalence post-legislation. These cardiovascular benefits reinforce the urgent need to enact and enforce smoke-free legislations that protect all citizens around the world from exposure to tobacco smoke in public places."

Tan, C.E.; Glantz, S.A., "Association between smoke-free legislation and hospitalizations for cardiac, cerebrovascular, and respiratory diseases: a meta-analysis," Circulation 126: 2177-2183, 2012.

This study performed a meta-analyis of 45 studies into the health impact of smokefree air laws and found that, "Comprehensive smoke-free legislation was associated with significantly lower rates of hospital admissions (or deaths) for all 4 diagnostic groups: coronary events (relative risk, 0.848; 95% confidence interval 0.816–0.881), other heart disease (relative risk, 0.610; 95% confidence interval, 0.440–0.847), cerebrovascular accidents (relative risk, 0.840; 95% confidence interval, 0.753–0.936), and respiratory disease (relative risk, 0.760; 95% confidence interval, 0.682–0.846)." The authors wrote, "Smoke-free legislation was associated with a lower risk of smoking-related cardiac, cerebrovascular, and respiratory diseases, with more comprehensive laws associated with greater changes in risk."

Olasky, S.J.; Levy, D.; Moran, A., "Second hand smoke and cardiovascular disease in low and middle income countries: a case for action," Global Heart 7(2): 151-160, July 1, 2012.

This paper stated, "A systematic review was conducted of MEDLINE-indexed studies of self-reported SHS exposure and cardiovascular harms in low- or middle-income nations. Eight papers reported the association of SHS with ischemic heart disease, and four reported the association of SHS with stroke. For all the studies, and almost all sources of SHS surveyed, a strong positive association between SHS and ischemic heart disease (main relative odds ratio range 1.17–2.36) and SHS and stroke (odds ratio or hazard ratio: 1.41–1.49). Prevalence of SHS exposure is high in low- and middle-income nations, especially among women. Epidemiologic evidence supports the conclusion that SHS harms are the same across low-, middle-, and high-income nations. Governments have an obligation to protect citizens from SHS exposure, enforcing smoke-free legislation and providing public education about SHS harms."

Mackay, D.F.; Irfan, M.O.; Haw, S.; Pell, J.P., "Meta-analysis of the effect of comprehensive smoke-free legislation on acute coronary events," Heart [Epub ahead of print], August 23, 2010.

This meta-analysis reviewed seventeen studies into the impact of smokefree air laws on heart attack rates. The authors noted that there was a significant body of evidence showing the heart attack rates decrease following the implementation of smokefree air laws and that this effect increases over time. The authors wrote that, "The pooled information from these studies suggests that acute coronary events fall by around 10% following the implementation of legislation," and recommended that, "Countries that have not yet implemented comprehensive smoke-free legislation should be encouraged to do so."

Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence
Institute of Medicine, October 2009

This report, issued by the Institute of Medicine, affirmed studies from around the world which reported dramatic reductions (ranging from 6%-47%) in heart attacks once smokefree laws are in place.

The IOM wrote of the findings, "Data consistently demonstrates that secondhand-smoke exposure increases the risk of coronary heart disease and heart attacks and that smoking bans reduce heart attacks. Given the prevalence of heart attacks, and the resultant deaths, smoking bans save more than half a million lives each year in the U.S. alone. The savings, as measured in human lives, is undeniable."

On October 15, 2009, Thomas R. Frieden, M.D., M.P.H. Director, Centers for Disease Control and Prevention, issued a statement regarding the report, in which he said:

"The report confirms that eliminating smoking in workplaces, restaurants, bars, and other public places is an effective way to protect Americans from the health effects of secondhand smoke, particularly on the cardiovascular system. The IOM also concluded that the evidence is compelling that even brief secondhand smoke exposure could trigger a heart attack.

Heart disease is the leading cause of death in the United States. Nearly three of four U.S. adults have at least one major risk factor for heart disease. Yet, only 40 percent of Americans live in areas with comprehensive state or local laws that ban smoking in public places. These findings suggest that tens of thousands of heart attacks could be prevented each year, and that states and communities that do not have comprehensive smoke–free laws could have significant cardiovascular health benefits by doing so.

There's no time to waste with this many lives at stake. It is time to mount a full–scale assault on the tobacco epidemic and eliminate all exposure to secondhand smoke. Smoke–free laws are one of the most readily available and cost–effective methods for preventing heart attacks, heart disease–related illnesses and deaths, and reducing health care costs. The only way to protect nonsmokers from the dangerous chemicals in secondhand smoke is to protect workers and the public through comprehensive smoke–free laws."

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CDC Page Regarding the IOM Report

Lightwood, J.M.; Glantz, S.A., "Declines in Acute Myocardial Infarction After Smoke-Free Laws and Individual Risk Attributable to Secondhand Smoke," Circulation [Epub ahead of print], September 21, 2009.

This meta-analysis of thirteen other studies, concluded that there is "...a significant drop in the rate of acute myocardial infarction hospital admissions associated with the implementation of strong smoke-free legislation. The primary reason for heterogeneity in results of different studies is the duration of follow-up after adoption of the law." The authors found that the benefit increased over time.

Meyers, D.G.; Neuberger, J.S.; He, J., "Cardiovascular Effect of Bans on Smoking in Public Places: A Systematic Review and Meta-Analysis," Journal of the American College of Cardiology, 54:1249-1255, 2009. Errata

This meta-analysis of eleven other studies into the impact of smokefree air laws on hospital admissions for acute myocardial infarction (AMI) found that the risk of AMI decreased by 8% overall following smokefree laws being implemented, with the greatest decreases among younger people and nonsmokers. The authors wrote, "Smoking bans in public places and workplaces are significantly associated with a reduction in AMI incidence, particularly if enforced over several years."

The authors estimated that if the entire United States were smokefree "as many as 156,400 new AMIs yearly" might be prevented.

Meyers, D.G.; Neuberger, J.S., "Cardiovascular effect of bans on smoking in public places," American Journal of Cardiology 102(10): 1421-1424, November 15, 2008.

This American Journal of Cardiology study used preliminary analysis of heart attack admissions in Helena, Montana; Pueblo, Colorado; New York; counties in Indiana; and Italy before and after clean indoor air policies were implemented. The authors found that acute myocardial infarction (AMI) hospital admissions fell in all locations after the laws were implemented. The researchers called on more studies in the matter to be done, but also encouraged medical professionals to support smokefree policies.