Archived Issues

2001, Volume 12, Number 3

Assessment of the Risk of Coronary Heart Disease

by Richard S. Bak, Ph.D.

On May 15th, the National Institutes of Health published the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on the Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults. This report is important because it recommends clinical practice guidelines for the assessment of risk for coronary heart disease (CHD), its prevention, and drug and non-drug therapies. This editorial will briefly review the report's recommendations for the risk assessment of CHD.

The report continues to identify elevated LDL cholesterol as the major cause of coronary heart disease and recommends its measurement as part of a lipoprotein analysis and identification of accompanying risk determinants. Specifically, the report recommends, in all adults aged 20 years or older, a complete lipoprotein profile (total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides) as the preferred initial test, rather than screening for total cholesterol and HDL alone. This profile should be obtained once every 5 years.

Besides LDL cholesterol, the report identifies age, elevated total cholesterol, low HDL cholesterol, elevated triglycerides, hypertension, and cigarette smoking as the major contributing risk factors to the development of CHD. It recommends that for the initial risk assessment, clinicians should use these major risk factors to define the core risk status. Only after the core risk status has been determined should any other risk factors be taken into consideration for adjusting the therapeutic approach.

Other, non-major risk factors recognized in the report include both life-habit risk factors and emerging risk factors. The former include obesity, physical inactivity, and atherogenic diet; the latter consist of lipoprotein (a), homocysteine, prothrombic and proinflammatory factors, impaired fasting glucose, and the evidence of subclinical atherosclerotic disease. The life-habit risk factors are direct targets for clinical intervention. The emerging risk factors can have utility in selected persons to guide intensity of risk-reduction therapy.

A combination of major, life-habit, and emerging risk factors is described in the report as the "metabolic syndrome". It is characterized by abdominal obesity, atherogenic dyslipidemia, raised blood pressure, insulin resistance, and prothrombotic and proinflammatory states. The syndrome is closely linked to the disorder called insulin resistance and its presence enhances the risk of CHD at any LDL cholesterol level. It is readily diagnosed in clinical practice using waist circumference and triglyceride, HDL cholesterol, and fasting glucose levels.

There are two other features of the report important to clinicians and laboratorians. The first is that the categorical low HDL cholesterol levels have been raised from < 35 mg/dL to < 40 mg/dL. The second is that lipoprotein phenotyping, LDL particle size distributions, and HDL subclass fractionations patterns, are not considered, in and of themselves, to be major or non-major risk factors by the NCEP.

We agree with the NCEP recommendations that the initial laboratory testing for the risk of coronary heart disease should consist of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. Tests for homocysteine, lipoprotein (a), hs-CRP, and others should be considered second tier testing to aid the clinician in his/her therapeutic approach. Alternatively, these tests can be ordered initially, if clinically indicated, on selected patients.

Clinicians and laboratorians are encouraged to read the entire NCEP report. It is available on the web at: www.nhlbi.nih.gov/guidelines/cholesterol/index.htm.

Warde
Medical
Laboratory