A population at risk: Prevalence of high cholesterol levels in hypertensive patients in the framingham study

Abstract

In the Framingham Study, coronary heart disease developed in every fifth man and every 17th woman by the age of sixty. The level of total cholesterol proved to be an excellent predictor of coronary heart disease in those aged less than 50 years. However, in those aged over 50 years, more accurate predictors of coronary heart disease risk were serum lipoprotein measurements, including low-density lipoproteins, very-low-density lipoproteins, very-low-density lipoprotein triglycerides, and high-density lipoproteins. Both low-density and very-low-density lipoproteins have a linear association with coronary heart disease. On multivariate analysis, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol are independently related to coronary heart disease risk in both sexes. In women, but not in men, very-low-density lipoprotein cholesterol or the triglyceride level is an independent risk factor on multivariate analysis. By likelihood ratio analysis, high-density lipoprotein is shown to be the most powerful single factor for predicting coronary heart disease risk in both sexes relative to the lipid fractions. It appears that one of the most reliable profiles in this regard is the ratio of total cholesterol to high-density lipoprotein cholesterol. However, a special constellation of elevated triglycerides, low high-density lipoprotein levels, and "normal" cholesterol values should no longer be overlooked in assessing coronary heart disease risk. Both systolic and diastolic blood pressures are also related to risk of coronary heart disease in a linear fashion: the higher the level of pressure, the greater the incidence of coronary heart disease. Blood pressure and serum cholesterol are correlated with an r factor of 0.12, suggesting that those with higher blood pressure values tend to have higher serum cholesterol levels. Most physicians agree that treatment is advisable in those with cholesterol levels above 300 mg/dl; some believe therapy is necessary in those with levels of more than 250 mg/dl. Few realize that half of the patients In whom coronary heart disease will eventually develop have cholesterol values under 250 mg/dl. The National Institutes of Health Consensus Development Conference on Lipid Lowering has recommended that cholesterol levels be reduced to 200 mg/dl in all persons. Practicing physicians argue that coronary heart disease does not develop in most patients with cholesterol levels between 200 and 250 mg/dl. The problem lies in deciding which patients with these cholesterol levels actually have a lipid abnormality. Measuring high-density lipoprotein levels may provide an answer. In the Framingham Heart Study, coronary heart disease developed with great consistency in patients with a ratio of total cholesterol to high-density lipoprotein cholesterol of more than 4.5. Half of the women and more than half of the men who present with treatable hypertension already have an abnormal lipid profile. Control of coronary heart disease should be multifactorial. Intervention should include therapy aimed at reducing blood pressure and lowering lipid levels, particularly low-density lipoprotein and very-lowdensity lipoprotein triglycerides. Since many antihypertensive agents have an adverse effect on lipids, considerable thought should be given to those drugs that represent a therapeutic alternative.