A population at risk. Prevalence of high cholesterol levels in hypertensive patients in the Framingham Study
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For individuals over 50, serum lipoprotein levels, particularly high-density lipoprotein cholesterol, are better predictors of coronary heart disease than total cholesterol. Elevated triglycerides and low HDL are key risk factors, even with normal total cholesterol.
Area of Science:
- Cardiology
- Preventive Medicine
- Lipid Metabolism
Background:
- Coronary heart disease (CHD) is a significant health concern, with incidence varying by age and sex.
- Total cholesterol is a known predictor of CHD, but its efficacy may differ across age groups.
Purpose of the Study:
- To identify the most accurate predictors of coronary heart disease (CHD) risk in individuals aged 50 and older.
- To compare the predictive power of serum lipoproteins versus total cholesterol for CHD.
Main Methods:
- Analysis of data from the Framingham Study.
- Multivariate and likelihood ratio analyses of serum lipid profiles (LDL, VLDL, HDL, triglycerides) and blood pressure in relation to CHD incidence.
- Correlation analysis between blood pressure and serum cholesterol levels.
Main Results:
- In individuals over 50, serum lipoproteins (LDL, VLDL, HDL) are more accurate CHD predictors than total cholesterol.
- High-density lipoprotein (HDL) cholesterol is the most powerful single predictor of CHD risk in both sexes.
- Elevated triglycerides, low HDL, and normal total cholesterol levels constitute a significant CHD risk profile.
- Systolic and diastolic blood pressures show a linear association with CHD risk.
Conclusions:
- Serum lipoprotein levels, especially HDL cholesterol, are crucial for assessing CHD risk in older adults.
- A lipid profile with elevated triglycerides and low HDL warrants attention, even with normal total cholesterol.
- Blood pressure remains a critical, independently assessed risk factor for coronary heart disease.
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.(ABSTRACT TRUNCATED AT 400 WORDS)