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.

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

©2011 Elsevier Ltd, Inc, BV

DOI: 10.1016/B978-1-4377-1160-8.10007-7

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

Rank

Cause

Number

1

Heart disease

598,747

2

Cancer (all types)

520,129

3

Stroke

131,312

4

Chronic lung disease

121,824

5

Alzheimer's disease

72,388

6

Diabetes mellitus

67,295

7

Accidents

57,089

8

Pneumonia and flu

53,676

9

Chronic nephritis

42,123

10

Septicemia

31,594

Data from http://webapp.cdc.gov/sasweb/ncipc/leadcaus.html. *All races, both genders; age groups: 50 to 85+.

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.

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

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

Intervention

Change in Disease-Specific Mortality*

Change in All-Cause Mortalityt

Primary Prevention

Pap smears

Cervical cancer: 20%-60% reduction after 17 or more Pap smears

0

Fecal occult blood testing (FOBT)

Sigmoidoscopy

Colonoscopy

Digital rectal examination (DRE)

Colorectal cancer: 15% reduction after 20 or more FOBTs plus follow-up colonoscopy in patients with positive results

0

Mammography: 40-50 years Mammography: >50 years

Breast cancer: 16% reduction after 20 mammograms

0

Prostate-specific antigen (PSA) testing DRE

Prostate cancer: 0% reduction after 25 PSA tests

0

DRE, breast self-examination (BSE), physical examination

0% reduction after 40 years

0

Statins (AFCAPS/TexCAPS Study)$

37% reduction in combined myocardial infarction, unstable angina, and stroke

0

Eight major lifestyle studies (see Tables 7-3 and 7-4): chronic disease and death

35%-83% reductions in coronary events 50%-71% reduction in stroke events 58%-93% reduction in onset of diabetes 36%-68% reduction in cancer deaths

40%-65%

Secondary Prevention

4S Simvastatin Study5

34% reduction in major coronary events

42% reduction in coronary mortality in patients with heart disease

30%

West of Scotland Coronary Prevention Study (WOSCOPS)lf

Statins reduced coronary events by 31% and cardiovascular specific mortality by 32%.

0

The MRC/BHF Heart Protection Study1

25% reduction in first-event rate for nonfatal myocardial infarction or coronary death, fatal or nonfatal stroke, and for coronary revascularization with 40-mg simvastatin in high-risk patients over 5 years in 20,536 U.K. adults age 40-80 years

12.9%

Beta blockers after myocardial infarction'

27% reduction of nonfatal infarction in 25 randomized trials (>23,000 patients)

22%

*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#r ationale; http://www.ahrq.gov/clinic/3rduspstf/cervcan/cervcanrr.htm; http://www.ahrq.gov/clinic/3rduspstf/breastcancer/brcanrr.htm; http://www.ahrq.gov/clinic/uspstf08/pro state/prostaters.htm.

fBlack 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. 1Heart 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.

endorsed explicit global cardiac risk assessment as the new standard of care:

Most current guidelines focus primarily on the management of individual cardiovascular risk factors, such as high blood pressure, hypercholesterolemia, or diabetes. A more appropriate clinical approach to reducing cardiovascular disease risk would be based on a comprehensive evaluation of risk profile, and accurate stratification of global (absolute) risk in individual patients. . . . The decision to treat a patient should be based on the level of global risk, rather than on the level of a single risk factor. . . . We proposed that global risk should be used as the main determination of whom to treat, how to treat, and how much to treat. . . . We propose to replace the single risk factor-based approach with the assessment of global cardiovascular risk, both in the clinical management of individual patients and in guidelines. (Volpe et al.,

2004)

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:

• Family history of CAD

• Hypertension

• Sedentary lifestyle

• Metabolic syndrome

• High cholesterol level

• Chronic renal insufficiency

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 singleintervention 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.

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.

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