. "4 Epidemiologic Studies of Secondhand-Smoke Exposure and Cardiovascular Disease." Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence. Washington, DC: The National Academies Press, 2010.
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Secondhand Smoke Exposure and Cardiovascular Effects: Making Sense of the Evidence
mittee reviewed that report, and this chapter alone should not be considered a comprehensive review of the published literature. For that, the reader is referred to the surgeon general’s report or other recent reports (Cal EPA, 2005; HHS, 2006; IARC, 2004). Recommendations for further research on the matter are presented in Chapter 7.
RISK FACTORS FOR ACUTE CORONARY EVENTS
Clinically manifest cardiovascular disease develops progressively. Extensive analyses of large cohorts show that the major risk factors for heart disease are smoking, diabetes, total cholesterol concentration, and hypertension (Wilson et al., 1998). Additional factors—such as obesity, left ventricular hypertrophy, C-reactive protein (CRP), and family history of heart disease at an early age—have been suggested as contributing to cardiovascular disease risk (Wilson et al., 1998). Data on three large prospective U.S. cohorts followed for 21–30 years indicate that exposure to at least one clinically increased major risk factor underlies 87–100% of cases of fatal coronary heart disease. For nonfatal coronary heart disease, the range was 87–92% (Greenland et al., 2003). An etiologic role of the major risk factors in the development of cardiovascular disease is indicated by extensive studies showing that treating or reducing exposure to risk factors lowers the rate of coronary heart disease events (Chobanian et al., 2003). That smoking is a major independent risk factor for coronary heart disease indicates that its effects cannot be entirely explained by changes in other risk factors and that it increases the incidence, development, and manifestation of cardiovascular disease by pathophysiologic mechanisms that are unique and relatively independent of dyslipidemia, hypertension, sex, or diabetes. Like active smoking, exposure to secondhand smoke could be considered an independent risk factor for cardiovascular disease.
EPIDEMIOLOGY OF CHRONIC EXPOSURE TO SECONDHAND-TOBACCO SMOKE IN RELATION TO CORONARYHEART DISEASE AND ACUTE CORONARY EVENTS
The surgeon general’s 2006 report concluded that “the evidence is sufficient to infer a causal relationship between exposure to secondhand smoke and increased risks of coronary heart disease morbidity and mortality among both men and women” and that “pooled relative risks from meta-analyses indicate a 25 to 30 percent increase in the risk of coronary heart disease from exposure to secondhand smoke” (HHS, 2006). This section provides an overview of the relationship between exposure to secondhand smoke and coronary events summarized in that report, not limited to acute coronary events. Much research has been conducted on secondhand-smoke