ESTIMATION OF CARDIOVASCULAR RISK - TOTAL CHOLESTEROL VERSUS LIPOPROTEIN PROFILE

The complete lipoprotein profile is thought to give more information a bout the individual risk of coronary heart disease than total choleste rol alone. Although total cholesterol has a low sensitivity in the cor rect assessment of the risk of coronary heart disease, it may be of va lue in screening programs because of its low cost. In this study of 5, 335 subjects, total cholesterol gave a different assessment of coronar y heart disease risk (United States National Cholesterol Education Pro gram guidelines) in 25% of subjects than the complete lipoprotein prof ile. Differences in risk assignment were mainly accounted for by high- and low-density lipoprotein-cholesterol (Friedewald equation). The ca lculated low-density lipoprotein-cholesterol was highly correlated wit h the value measured with a mixed ultracentrifugation and precipitatio n procedure. However, calculated values gave estimates of coronary hea rt disease risk which were 20% different from those from measure value s. In 200 subjects in whom the lipoprotein profile was assessed three times in 1 year, the total cholesterol low-density lipoprotein-cholest erol varied by more than 30 mg/dl (0.78 mmol/1) in 52% and 50%, respec tively, triglycerides by more than 30 mg/dl (0.34 mmol/1) in 75%, and high-density lipoprotein-cholesterol by more than 15 mg/dl (0.39 mmol/ 1) in 34%. Compared with the mean of the measurements, the single meas urement of total cholesterol misclassified 48% of subjects, low-densit y lipoprotein-cholesterol 60%, high-density lipoprotein-cholesterol 12 %, and 28%. We conclude that total cholesterol alone may be misleading in the assignment of coronary heart disease risk. Calculation of low- density lipoprotein-cholesterol, although less accurate than desirable , is the only way of evaluating this in clinical practice. Finally, re peated lipid measurements are required to assess coronary heart diseas e risk accurately.