Prevention from the Disease-Oriented Perspective: A Focus on Heart Disease

To be effective, family physicians need to reduce mortality—from all causes, not just heart disease or stroke—for all their patients. Using the total number of deaths is the relevant measure of effectiveness for two reasons. First, it is simple, cleaner, and easier to measure; a person is either alive or dead. Second, the count is not affected by diagnostic error. The literature reviewed here focuses especially on all-cause mortality as a relevant measure of a healthy lifestyle.

In the United States the system for counting numbers of deaths is provided by the Centers for Disease Control and Prevention (CDC) through its Wisqars database. Simply type the search term leadcaus.html into Google, and the database will be the first link to appear. The variables for gender, age, ethnicity, and U.S. region can be changed to best fit where you are working.

The leading causes of death for all adults age 50 to 85 are listed in Table 7-1. A look at this list can provide a guide to action for your practice. If the number-one cause of death is heart disease, this may be the problem to address most vigorously, perhaps delaying other preventive activities until this is done. Alternatively, some might argue for a focus on cancer, because mortality from cancer is almost as high as from heart disease (and even higher in the age group 50-59), and cancer causes much more concern among patients.

Table 7-1 Ten Leading Causes of Death—United States, 2006^∗

∗ All races, both genders; age groups: 50 to 85+.

Data from http://webapp.cdc.gov/sasweb/ncipc/leadcaus.html.

However, good reasons exist not to focus on cancer. The first problem is that “cancer,” when listed as the second leading cause of death in the United States, represents deaths from “all cancers.” The disadvantage is that physicians have no good tools or tests that work against “all” cancers; the single exception is discussed later. Many mammograms are needed for breast cancer, many sigmoidoscopies or colonoscopies for colon cancer, and many Pap smears for cervical cancer, to follow the conventional wisdom about how to reduce the effects of these cancers.

Such a strategy is only moderately effective. The risks of dying of breast cancer can be reduced by only 15% in the 3% of women who develop it in any decade after age 50 (Fletcher and Elmore, 2003). The risk of dying of colon cancer (incidence from 57 to about 320 for both genders ages 50-80 [Eddy, 1990]) can be reduced by only 16%. The single best strategy for reducing deaths from a cancer is cervical cancer screening; cervical cancer deaths can be reduced for the seven or eight invasive cervical cancers that occur annually per 10,000 population by 30% to 60% (Agency for Healthcare Research and Quality [AHRQ], U.S. Preventive Services Task Force [USPSTF], 2009).

Because these cancers are relatively rare, however, and because the tools are relatively inefficient, a cancer-focused approach to reducing overall mortality tends not to work. In fact, a 2002 review of cancer screening concluded that there is no evidence that cancer screening, as currently conducted, results in reductions of all-cause mortality (Black et al., 2002). Thus, even perfect compliance for all the traditionally recommended cancer programs may dramatically reduce a person’s risk of dying of cancer, but it would not add a single day of life to this person’s life span. Table 7-2 illustrates the failure of most cancer screening programs, even when they have a significant impact on the target cancer, to alter the ultimate bottom line: all-cause mortality.

Table 7-2 Comparison of Disease-Specific Mortality and All-Cause Mortality Associated with Traditional Cancer and Cardiovascular Prevention Strategies

∗ All data from current U.S. Preventive Services Task Force (USPSTF) appraisal of the evidence and recommendations. http://www.ahrq.gov/clinic/uspstf08/colocancer/colors.htm#rationale; http://www.ahrq.gov/clinic/3rduspstf/cervcan/cervcanrr.htm; http://www.ahrq.gov/clinic/3rduspstf/breastcancer/brcanrr.htm; http://www.ahrq.gov/clinic/uspstf08/prostate/prostaters.htm.

† Black WC, Haggstrom DA, Welch HG. All-cause mortality in randomized trials of cancer screening. J Natl Cancer Inst 2002;94:167-173.

‡ Downs JR et al., for AFCAPS/TexCAPS Research Group. Primary prevention of acute coronary events with lovastatin in men and women with average cholesterol levels: results of AFCAPS/TexCAPS. JAMA 1998;279:1615-1622.

§ Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4444 patients with coronary heart disease: the Scandinavian Simvastatin Survival Study (4S Study). Lancet 1994;344:1383-1389.

⁋ Shepherd J et al., for West of Scotland Coronary Prevention Study Group. Prevention of coronary heart disease with pravastatin in men with hypercholesterolemia. N Engl J Med 1994.

¶ Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002;360:7-22

# Yusuf S, Wittes J, Friedman L. Overview of results of randomized clinical trials in heart disease. I. Treatments following myocardial infarction. JAMA 1988;260:2088-2093.

Physicians are familiar with measuring the effectiveness of screening in terms of relative risk reductions. The most dramatic numbers relating to personal medical efficacy pertain to the interventions proven to work for established coronary artery disease (CAD), called secondary prevention. The most impressive numeric successes a good physician can achieve are the 20% to 40% reductions in heart disease events that result when persons with heart disease take statin medications regularly (4S Study, 1994; Heart Protection Study, 2002; Sheperd et al., 1994), or when patients who have had a heart attack use a beta-adrenergic blocker after their heart attack, which reduces the risk of recurrent myocardial infarction by 22% (Yusuf et al., 1988).

Secondary prevention is often preferable to physicians because benefits of large effect size can be seen after relatively short periods of intervention (only a few years). Physicians who focus on cancer prevention need to wait for 20 to 40 years to know how well the program worked. For example, Pap smears are recommended from age 21 to age 65 at about 3-year intervals; colon cancer screening is recommended annually from ages 50 to 75; and breast cancer screening typically from ages 40 to 85. The published data on efficacy refer to the entire lifetime of the screening program, so it takes a long time to see the benefit of what physicians do.

A short list of the most important interventions, those with large effect size in secondary prevention, are also summarized in Table 7-2. Physicians preferring the disease treatment model for medicine who want to believe their work is important and measurably effective should select at least one strategy from this table.

The prevention of heart disease, both primary and secondary, should be the first priority for primary care physicians. The critical question is how to do this. Most physicians focus on obvious risk factors, such as smoking, hypercholesterolemia, and diabetes. These same physicians are usually surprised to discover the evidence indicates that physicians who rely on a subjective “gestalt” for risk assessment usually make significant errors (Grover et al., 1994; Volpe et al., 2004). When physicians assess clinical coronary risk based on the major cardiac risk factors, they systematically tend to overtreat modest to severe elevations of a single risk factor, even when the global cardiac risk is quite low. Similarly, if they do only subjective risk factor assessment, physicians fail to offer treatment to many patients at high global cardiac risk merely because they lack any major risk factors or have only a mild abnormality of a few risks. A common example of misdirected treatment is prescribing a statin for a 40-year-old woman with a cholesterol level of 300 mg/dL but no other risk factors; according to the Framingham equation, she has a 10-year risk of a cardiac event of 2%, which is average for her age. To treat patients appropriately, the clinician must use one of the global risk calculators mentioned later.

Why focus on global cardiac risk? Leading national and specialty-based expert groups have endorsed this as the most important parameter for addressing cardiac health (Grundy et al., 1999). The Adult Treatment Panel Report (ATP II) of the National Cholesterol Education Program (NCEP), the Joint National Committee of the National High Blood Pressure Education Program, and the American Diabetes Association (ADA) all advocate “adjusting the intensity of risk factor management to the global risk of the patient.” The NCEP Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III, 2001) stated specifically, “A basic principle of prevention is that the intensity of risk-reduction therapy should be adjusted to a person’s absolute risk. Hence, the first step in selection of LDL-lowering therapy is to assess a person’s risk status…. In ATP III, a primary aim is to match intensity of LDL-lowering therapy with absolute risk.” Hypertension experts John Laragh, Bruce Psaty, and Curt Furberg have directly endorsed explicit global cardiac risk assessment as the new standard of care:

Once the importance of carrying out some form of global cardiac risk assessment is accepted, a physician need only choose a method and use it consistently. A basic quality-of-care goal process standard would be to use the method of CAD risk assessment systematically for at least 85% of all adult patients over 85% of all years. There are many ways to carry out cardiac risk assessment—from the Framingham tables and equation (United States), by means of the NCEP ATP III risk calculator, to the Sheffield tables and the most recent technique, the QRISK calculator (United Kingdom) (Hippisley-Cox et al., 2008; Wallis et al., 1995). Many of these have been adapted for smart phones and personal digital assistants (PDAs) and are downloadable for free, so few major barriers to implementation exist, primarily time.

A time-efficient method that can be used in the office setting includes a preprinted list of the 10 major cardiac risk factors supported by the current literature. Consider making a list that can be incorporated into the patient’s medical record, including the following:

Other considerations include major adverse life event and high perceived stress at work or home.

The purpose of this list is to classify all adults into one of three levels of risk: low, intermediate, or high. Where the dividing lines are drawn between categories is not as important as being consistent. In my practice, I consider up to three risk factors to be low risk, four to six factors to be intermediate risk, and more than six, high risk. This information (e.g., CAD Risk Score: “intermediate risk”) should go directly into the problem list so that the physician can see it each visit. The intervention itself is relatively inexpensive, requiring only 1 to 2 minutes of physician (or better, medical assistant) time and involving simple laboratory tests—lipid panel and serum creatinine. I define the “metabolic syndrome” as a triglyceride level greater than 150 mg/dL and high-density lipoprotein (HDL) level less than 40 mg/dL for men (or <50 for women), according to the Reaven (2003) criteria. A serum creatinine is obtained to estimate glomerular filtration rate (GFR) and identify the presence of chronic renal insufficiency.

For patients at low global cardiac risk, nothing more is required than usual care, which should include conversations about diet, exercise, not smoking, and stress reduction. For persons at either intermediate or high risk, more is required. The physician should systematically apply the best evidence for reducing cardiac risk. This is now a sophisticated and effective set of measures.

For patients at high risk, it would be worth having a discussion about the formal “polypill” approach (Wald and Law, 2003). This strategy recommends daily intake of folic acid, a statin, aspirin (81 mg), along with half-doses of three different antihypertensives (hydrochlorothiazide, beta blocker, and ACE inhibitor). The proponents of this strategy claim that the polypill can reduce heart attacks and stroke (third leading cause of mortality) by more than 80% in both primary and secondary prevention. Although no reported randomized, controlled trials (RCTs) have yet proved this for primary prevention, one study showed major benefit in secondary prevention (Hippisley and Coupland, 2005), and more studies are under way.

All physicians should understand that the advances in conservative medical therapy for cardiovascular disease have kept pace and may well have outpaced the advances in the technology of heart disease (e.g., drug-eluted stents) with far fewer complications.

The power of global cardiac risk assessment lies in the synergies achieved with the simple medical interventions to address increased risk. Figure 7-1 illustrates how a single-intervention health promotion program using only “CAD Risk Assessment” and the appropriate conservative responses previously listed achieve multiple synergistic benefits across a large spectrum of diseases and the 10 leading causes of death.

Figure 7-1 A single intervention with a simple, comprehensive medical approach to coronary risk has a significant impact on all 10 of the most common causes of death in the United States. A line is drawn from each of 10 potential cardiac risk interventions on the left side to all the causes of death that each intervention would also tend to reduce.

The largest component of the previously described intervention program is basically the promotion of a healthy lifestyle. When applying the best evidence, it is impossible to prevent only heart disease. Appropriate interventions have a significant effect on almost all the 10 leading causes of death. Thus, even a single-minded focus on the prevention of just one disease (heart disease) inevitably leads to a broad focus on lifestyle behavioral changes.

Primary Prevention: A Focus on Lifestyle

Key Points

A clinical practice may choose a broad, primary prevention approach rather than a single focus on prevention of coronary heart disease. Between 2000 and 2009, nine major studies demonstrated that a healthy lifestyle is associated with large reductions in all-cause mortality and major reductions in multiple disease-specific outcomes. These studies succinctly define what should be understood by the term “healthy lifestyle.” These primary prevention studies demonstrate that persons who have a number of healthy characteristics at the beginning of a period of observation enjoy remarkable benefits over periods ranging from 4 to 20 years.

The evidence chain begins with the Nurses’ Health Study (Hu et al., 2001; Stampfer et al., 2000). In 84,129 participants followed up for 14 years, the effects of several lifestyle factors were analyzed, including not currently smoking, body mass index (BMI) less than25 kg/m², alcohol consumption at least 0.5 drinks per day, at least 0.5 hour daily of moderate to vigorous physical activity, and adhering to several dietary elements (increased intake of cereal fiber, marine omega-3 fatty acids, and folate; increased polyunsaturated/saturated fat ratio; and low trans fat intake and glycemic load). The group defined as “low risk” had all these characteristics. After 14 years, this low-risk group (3% of original study population) had an 83% reduction in coronary disease events. Another analysis of the same cohort showed that women at low risk also had a 91% reduction in the risk of developing diabetes.

In 2002 the Diabetes Prevention Program Research Group published the results of the only RCT among these lifestyle studies. This study focused solely on the outcome of type 2 diabetes among 3324 nondiabetic patients. The “standard” healthy lifestyle intervention consisted of written information provided at the beginning of the study and an annual 20- to 30- minute individual counseling session. The defined “standard” lifestyle goals included instructions to adhere to the U.S. Department of Agriculture (USDA) Food Guide Pyramid and the equivalent of an NCEP Step 1 diet; to reduce weight; and to increase physical activity. Subjects were randomized to standard lifestyle intervention plus metformin (875 mg twice daily), to standard lifestyle intervention plus placebo, or to “intensive” lifestyle intervention alone. The latter group was encouraged to achieve and maintain a weight reduction of at least 7% of initial body weight through a healthy low-calorie, low-fat diet and to engage in physical activity of moderate intensity, such as brisk walking, for at least 150 minutes per week. Subjects in this group also received a 16-lesson curriculum, taught by case managers on a one-to-one basis during the first 24 weeks after enrollment, with brief follow-up sessions monthly. After an average follow-up of only 2.8 years, the intensive lifestyle intervention was associated with a reduced incidence of diabetes (58% vs. 31% reduction with metformin, both compared to placebo). The intensive lifestyle intervention was significantly more effective than the standard lifestyle intervention plus metformin.

In the Healthy Aging: A Longitudinal Study in Europe (HALE Project), in 2539 participants age 70 to 95 at baseline, investigators found a 65% reduction in all-cause mortality and 67% to 77% reductions in disease-specific risks for coronary heart disease, any cardiovascular disease, and cancer in the group with four healthy lifestyle factors (never smoking, Mediterranean diet, 3-4 hours/week of moderate physical activity, and glass of wine or more daily) compared with the group with none of these healthy characteristics (Knoops et al., 2004).

The Women’s Health Study analyzed smoking, alcohol use, exercise, BMI, and diet among 37,636 participants age 45 or older. After a mean of 10 years follow-up, there were risk reductions of 55% for total stroke and 71% for ischemic stroke; the risk-adjusted hazard ratio for participants who scored higher on an index of lifestyle factors than those who scored lower was 0.45 for total stroke and 0.29 for ischemic stroke (Kurth et al., 2006).

In the Health Professionals Follow-up Study, 42,847 men age 40 to 75 were followed over 16 years using similar healthy lifestyle criteria. “Low risk” was defined as the absence of smoking, BMI less than 25 kg/m², moderate to vigorous activity of at least 30 minutes a day, moderate alcohol consumption (5-30 g/day), and the top 40% of the distribution for healthy diet score. Compared with men with no healthy lifestyle factors, those with all five factors had an 87% reduction in the risk of developing coronary heart disease (Chiuve et al., 2006).

In the Atherosclerosis Risk in Communities Study (ARIC), the effects of four healthy lifestyle factors (≥5 servings of fruits and vegetables per day, ≥2.5 hours of exercise per week, BMI of 18.5-30 kg/m², not smoking) were analyzed in 15,708 participants followed for only 4 years. Among subjects who had no healthy characteristics at baseline, those who changed their behavior and adopted a healthy lifestyle (all four habits) experienced a lower risk (40% reduction) of all-cause mortality and a 35% reduction in cardiovascular disease (King et al., 2007). This study is particularly important because it indicates clearly that those with a relatively unhealthy lifestyle who change in midlife can still achieve dramatic reductions in health risks and longer life expectancy.

The European Prospective Investigation into Cancer and Nutrition (EPIC)–Norfolk study demonstrated significant reductions in all-cause mortality with increasing numbers of health factors in 20,244 participants followed for a mean of 11 years. The four factors analyzed were current nonsmoking status, engaging in regular physical activity, moderate alcohol use, and plasma vitamin C level greater than 0.88 ng/dL, as a surrogate for fruit and vegetable consumption. Individuals with all four factors had an advantage of approximately 14 years in chronologic age over those with only one of the four factors (Khaw et al., 2008).

Further follow-up analysis of the 43,685 individuals in the Health Professionals Follow-up Study and the 71,243 participants in the Nurses’ Health Study showed that a healthy lifestyle was associated over time with a 69% reduction in the risk of developing an incident stroke among men and a 79% reduction of stroke risk among women (Chiuve et al., 2008).

The most recent major study in this line of evidence that changes in lifestyle behavior lead to remarkable changes in health outcomes is the “Healthy Living Is the Best Revenge” report. Ford and colleagues (2009) used data from 23,153 German participants age 35 to 65 from the European Prospective Investigation into Cancer and Nutrition (EPIC)–Potsdam study. They analyzed end points of type 2 diabetes mellitus, myocardial infarction, stroke, and cancer and the effect of four healthy lifestyle factors: never smoking, BMI less than 30 kg/m², 3.5 hours/week of physical activity or more, and adhering to healthy dietary principles (high intake of fruits, vegetables, and whole-grain bread; low meat consumption). Fewer than 4% of participants had zero healthy factors; most had one to three healthy factors, and 9% of the group had all four factors. During a follow-up of 7.8 years, after adjusting for age, gender, educational status, and occupational status, the hazard ratio for developing a chronic disease decreased progressively as the number of healthy factors increased. Participants with all four factors at baseline (vs. those with none) had a 78% lower risk of developing a chronic disease. The risk of developing diabetes was reduced by 93%, the risk of myocardial infarction by 81%, risk of stroke by 50%, and risk of cancer by 36%.

The results of these studies are summarized in Tables 7-3 and 7-4. Despite minor variations, there is now substantial consensus on what constitutes a “healthy lifestyle.” Briefly stated, a healthy lifestyle consists of the following:

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