Page 777 - Cardiac Nursing

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D D D Disease Prevention
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C C C C Coronary Heart Disease Risk Factors
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M. Kaye Kramer / Katherine M. Newton /
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Erika S. Sivarajan Froelicher
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Coronary heart disease (CHD)) is usually associated with one or more th throughout theeir lifee spans. Death rates from MI increasee with age
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characteristics known as risk factors. A risk factor is “an aspect of per- in in meen and women. CHD incidence in women lagss approxi-
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sonall behavioor or liffest le, an en ironmenttall exposure, or ann inbborn mately 100 years behind that in men, and there is approximately a
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or inherited characteristic, which on the basis of epidemiologgic evi- 20-yyear lag forr serioous clinical events such ass CHD mortality 4 4
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dence is known to be associated with” the occurrence of disease. 1 (Fig. 32-2). Data from the Behavioral Risk Factor Surveillance
Several aspects of the association between a potential risk factor System (BRFSS) in 2005 showed that the prevalence of a reported
and the disease are evaluated before an association is considered history of MI was highest for the American Indian/Alaskan Native
causal. These include the strength or magnitude of the association, population (7.4%) and lowest among Asians (2.9%) (Table 32-1).
the consistency or repeatability of the association, temporality (the CHD mortality rates have declined steadily since the late 1960s.
cause precedes the disease), dose response (greater dose leads to From 1968 to 1984, CHD mortality declined at an average rate of
greater likelihood of disease), the biologic and epidemiologic 2% to 3% per year in all age groups, in both sexes, and in black and
5
plausibility of the association, coherence of the potential cause white subjects. Overall, cardiovascular disease death rates declined
4
with what is known about the disease, a decrease in the incidence 24.7% from 1994 to 2004. There is ongoing speculation as to the
of disease when the potential cause is eliminated, and experimen- cause of this decline in cardiovascular disease mortality, although
tal evidence. 2,3 Although few potential risk factors meet all of multiple causes are likely. Decreases in case fatality rates have been
these criteria, the goal of epidemiologic investigations is to estab- documented. This indicates that changes in patient management,
lish these characteristics. The results of epidemiologic studies of including more rapid access to emergency care and interventions
disease cause are frequently presented either as disease rates or as that reduce infarct size and prevent death caused by arrhythmias,
6
a relative risk. The relative risk is the rate of disease in a group ex- may account for some of the decline in CHD mortality. One re-
posed to a potential risk factor, divided by the rate of disease in an cent study which examined the decrease in CHD mortality between
3
otherwise similar group that is unexposed to the risk factor. For 1980 and 2000 determined that approximately 47% of the decrease
example, if the rate of fatal myocardial infarction (MI) in a group was attributed to evidence-based medical treatments such as sec-
of smokers was 120 per 100,000 per year, and the rate in compa- ondary preventive therapies after MI or revascularization, treatment
7
rable nonsmokers was 60 per 100,000 per year, then the relative for acute MI, angina and heart failure, and other therapies. Ap-
risk associated with smoking would be as follows: proximately, 44% of the decrease was attributed to changes in risk
factors in the population, such as decreases in total cholesterol, sys-
rate in exposed
Relative risk tolic blood pressure, physical inactivity, and smoking.
rate in unexposed Cardiovascular disease risk factors have additive effects. The MI
risk in a person with three major risk factors is higher than that of
120> 3100,000 per year4 8
a person with two or one. Furthermore, for any given combina-
60>3100,000 per year4 tion of risk factors, at a given age, the risk is lower in women than
in men; however, the risk for CHD increases dramatically in
2.0 women after menopause. In this chapter, the major known risk
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factors for cardiovascular disease are briefly reviewed.
The risk of MI is thus doubled in the smokers, or there is a
200% increase in risk compared with nonsmokers. A relative risk
of 1.30 represents a 30% increase in risk; a relative risk of 3.0 rep-
resents a 300% increase, or a tripling of risk. United States death DEMOGRAPHIC
rates in 1998 from all cardiovascular diseases combined, acute MI, CHARACTERISTICS
cancer, and other causes, for black and white women and men are
presented in Figure 32-1. Cardiovascular disease continues to be CHD mortality rates increase exponentially with age for men and
the leading cause of death for black and white men and women women (Fig. 32-2). Until the seventh decade of life, black men
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