Effective Use of Statins to Prevent Coronary Heart Disease.

Publication: American Family Physician

Publication Date: 15-JAN-01

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COPYRIGHT 2001 American Academy of Family Physicians

Primary and secondary prevention trials have shown that use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (also known as statins) to lower an elevated low-density lipoprotein cholesterol level can substantially reduce coronary events and death from coronary heart disease. In 1987 and 1993, the National Cholesterol Education Program promulgated guidelines for cholesterol screening and treatment. Thus far, however, primary care physicians have inadequately adopted these guidelines in clinical practice. A 1991 study found that cholesterol screening was performed in only 23 percent of patients. Consequently, many patients with elevated low-density lipoprotein levels and a high risk of primary or recurrent ischemic events remain unidentified and untreated. A study published in 1998 found that fewer than 15 percent of patients with known coronary heart disease have low-density lipoprotein levels at the recommended level of below 100 mg per dL (2.60 mmol per L). By identifying patients with elevated low-density lipoprotein levels and instituting appropriate lipid-lowering therapy, family physicians could help prevent cardiovascular events and death in many of their patients. (Am Fam Physician 2001;63:309-20,323-4.)

An elevated low-density lipoprotein (LDL) cholesterol level is a key risk factor for coronary heart disease (CHD). The National Cholesteral Education Program (NCEP) first recommended universal cholesterol screening in 1987.(1) The National Ambulatory Medical Care Survey showed that family physicians and general internists in 1990-91 screened only 23 percent of adult patients for dyslipidemias and prescribed lipid-lowering medications for only 23 percent of patients with dyslipidemias.(2) Almost one decade later, many physicians still do not routinely perform cholesterol screening. Family physicians seldom include lipid screening in well-woman visits, and lipid screening is seldom done during visits for acute illness by young-adult and middle-aged men, most of whom are unlikely to return for health maintenance visits.

Despite multiple randomized trials showing that a reduction in an elevated LDL level lowers cardiovascular morbidity and mortality,(3-5) most patients with high LDL levels remain unidentified or untreated.(2) In addition, many physicians are uncertain about when to start preventive treatment. Although dietary change can be effective in reducing the LDL level,(6) most patients are unwilling or unable to modify their eating habits sufficiently enough to achieve LDL treatment goals. In addition, patients who have no symptoms of CHD often do not perceive the need for or do not want to begin long-term drug therapy, sometimes lasting decades, to prevent future cardiovascular problems. Some are concerned about possible drug side effects, and the cost of lipid-lowering medication can also be a factor that discourages treatment.

Lipid Management: An Overview of Prevention

The family physician is uniquely positioned to detect lipid problems in multiple family members and to facilitate long-term compliance with cholesterol treatment. Prevention of cardiovascular disease ideally begins with primary interventions in persons with no known cardiovascular disease.(7) The physician's role in primary prevention is to assess CHD risk factors (Table 1), urge lifestyle changes and initiate medical treatment in high-risk patients. The goal of secondary prevention in patients with atherosclerotic disease is to lower the risk of subsequent CHD events. Clinical trials have shown that most patients with CHD are candidates for lipid-lowering medication.(8) Individuals with CHD carry a five- to sevenfold increased risk of recurrent CHD events and are most likely to benefit from lipid-lowering therapy.(4,5,9)

LIPID SCREENING GUIDELINES

NCEP guidelines recommend lipid screening in all adults by means of a lipid profile or total cholesterol and high-density lipoprotein (HDL) cholesterol determinations.(10,11) This recommendation for screening cholesterol includes the elderly population, for whom evidence of treatment benefit was lacking but is now beginning to emerge.(12) To maximize cooperation from the patient, the NCEP recommends screening with nonfasting blood specimens.(10) Random specimens often yield useful information about the postprandial rise in triglyceride levels and the related risk for atherosclerosis.(13) It should be kept in mind that acute illness can alter blood lipids, especially if the liver or thyroid is affected.

The main goal of screening is to identify patients with elevated LDL levels. If screening values are abnormal, follow-up testing should be conducted in each of the following circumstances:

* Total cholesterol higher than 200 mg per dL (5.15 mmol per L) and other cardiac risk factors

* Total cholesterol higher than 240 mg per dL (6.20 mmol per L)

* HDL less than 35 mg per dL (0.90 mmol per L)

The NCEP goal for LDL levels depends on each patient's risk factor status (Table 2). The NCEP recommends checking lipid levels every five years in patients without CHD risk factors and every one to two years in patients with CHD risk factors.(10) In most persons, LDL and HDL levels are relatively stable over the long term. Much expense would be saved if individuals with healthy LDL and HDL levels were rescreened less often than is recommended or than is requested by some patients.

DIETARY MODIFICATION

Dietary modification is usually the first intervention in patients with borderline-high or moderately elevated LDL levels. However, patients with elevated LDL levels despite a low-fat intake have little room for dietary change. They frequently have type IIa or IIb dyslipidemia.

A fasting lipid profile should be obtained four to six weeks after the start of dietary therapy. The change in the LDL level as a result of a reduction in the average daily intake of saturated fat and cholesterol occurs in the first few weeks after the initiation of dietary modifications.(14) With a given amount of dietary change, lipid levels do not show further improvement as the patient continues to adhere to the low-fat diet for a longer period. Although the NCEP recommends a six-month trial of dietary therapy before drug therapy is considered in patients without CHD, patients seldom maintain dietary changes for as long as six months without receiving feedback on the response of their lipid levels to the dietary changes.

Pharmacologic Treatment for Primary Prevention of CHD

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