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Introduction
Hyperlipidemia
is a risk factor for accelerated vascular disease. It is a major
modifiable risk factor for coronary artery disease, cerebrovascular
disease, and peripheral vascular disease. The most aggressive treatment
of elevated lipids should be reserved for those patients at highest
risk for vascular disease:
- Patients
with a documented history of coronary artery disease, cerebrovascular
disease, or peripheral vascular disease.
- Patients
with a history of diabetes or hypertension.
- Patients
with two or more risk factors for vascular disease.
- Patients
with an LDL-C level above 160 mg/dL.
- Patients
with elevated triglycerides, low levels of HDL cholesterol, and
those who smoke.
Screening
recommendations for the general population are:
- Every 5 years
for males age 35-65
- Every 5 years
for females age 45-65.
Screening
for adults under age 35 and over age 65 should generally be limited
to those with risk factors for vascular disease which include:
- Family history
of premature vascular disease
(<50 male, <60 female)
- Smoking
- Hypertension
- Diabetes
- Documented
vascular disease
Elevated
cholesterol levels are generally classified as:
- Desirable: TC<200 mg/dL, HDL>35 mg/dL, LDL<130
- Borderline: TC 200-239, HDL>35 mg/dL, LDL 131-160, and fewer
than 2 risk factors and without vascular disease
- High: presence of vascular disease and LDL>160 or TC>240
mg/dL or HDL <35 mg/dL, or 2 or more risk factors.
- An additional factor to consider is the total cholesterol/HDL
ratio. The goal is to keep the ratio below 5:1; the optimum ratio
is 3.5:1.
Treatment
The treatment
of hyperlipidemia is based on the "stepped care" model.
This involves classifying the severity of the patient's lipid elevations
and risk factors, then beginning treatment with diet and progressing
to more aggressive treatment in a step-wise fashion. Patients who
have made no attempt to change their diet and who are not at high
risk for vascular disease should generally begin with the Step 1
diet and advance to the Step 2 diet only if their lipid levels do
not reach goal. Patients classified as high risk should proceed
directly to Step 2 diet.
- Step 1: Provide
information on dietary modification, physical activity, and risk
factor reduction. Diet should generally consist of =<30% fat, <8-10% saturated fat, <300 mg/d cholesterol.
- Step 2: Provide
information on dietary modification, physical activity, and risk
factor reduction. Diet should generally consist of =<30% fat, <7% saturated fat, <200 mg/d cholesterol.
Patients who
fail maximal diet therapy may be candidates for drug therapy.
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Risk Category
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Goal LDL
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Without
CHD and with fewer than two risk factors
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<
160 mg/dL
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Without
CHD and with two or more risk factors
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<
130 mg/dL
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With CHD
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100 mg/dL
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Medication
Selection
- The drugs
of first choice for elevated LDL cholesterol are the bile acid
sequestrants (cholestyramine, colestipol) and nicotinic acid (niacin).
These medications are effective and have no serious side effects.
They can have troublesome side effects requiring member education
to improve compliance. Niacin is preferred in the presence of
elevated triglycerides (exceeding 250 mg/dL). Bile acid sequestrants
should not be used as a single agent in the presence of elevated
triglycerides.
- HMG CoA reductase
inhibitors (lovastatin, pravastatin, fluvastatin, and simvastatin)
are very effective for lowering LDL levels in patients who do
not tolerate or respond to the first line agents of choice.
- Fibrates
(Gemfibrazil and clofibrate) have moderate effects on LDL levels
but are more effective in lowering elevated triglycerides.
- Combination
therapy may be used on high risk patients who fail to respond
to diet and single agent medication regimens. Combining a bile
acid sequestrant with either nicotinic acid or an HMG CoA reductase
inhibitor can markedly lower LDL levels.
Monitoring
Guidelines
- Once a patient
has been diagnosed with hyperlipidemia, measure LDL/lipid profiles
on a regular basis, at least annually.
- After initiation
of drug therapy, measure LDL levels at 4 to 6 weeks and repeat
again in 3 months.Monitor
for cholesterol response and side effects of therapy.
- If response
is adequate, i.e., the goals above are met, continue to monitor
every 4 to 6 months.
- If inadequate
response, use a combination of 2 drugs or switch to a different
agent. Combination therapy is most useful for those with severe
hypercholesterolemia and combined hyperlipidemia.
References
Second Report
of the Expert Panel on Detection, Evaluation, and Treatment of High
Blood Cholesterol in Adults. NIH Publication number 93-3095. September
1993.
Schwartz, JS, The Cost-Effectiveness of Cholesterol Lowering Therapy:
A Guide for the Perplexed. JCOM. 1996;3(6):48-51.
Grundy, et. al., When to Start Cholesterol-Lowering Therapy in Patients
with Coronary Artery Disease. Circulation. 1997;95:1693-1685. American
College of Physicians. Guidelines for Using Serum Cholesterol, HDL
Cholesterol, and Triglyceride Levels as Screening Tests for Preventing
Coronary Heart Disease in Adults. Annals of Internal Medicine. 1996;124(5):515-517.
Garber, et al, Cholesterol Screening in Asymptomatic Adults Revisited.
Annals of Internal Medicine. 1996;124(5):518-531.
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