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New Cholesterol Guidelines - 2013

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In November, 2013, a panel of experts from the American Heart Association and the American College of Cardiology, convened by the National Heart, Lung, and Blood Institute (NHLBI), released their long-awaited, updated guidelines on the treatment of cholesterol.  The last set of official  cholesterol guidelines were published in 2003 and last updated in 2004, and a lot of new information about cholesterol and its treatment has come to light since then. Accordingly, the new guidelines constitute a fairly striking change,

On the surface, the most obvious difference between these new guidelines and the old ones is that the new guidelines no longer recommend that doctors aim therapy toward specific target cholesterol levels. On a deeper level, the new guidelines are important in what they really say about cholesterol, cardiac risk - and the statin drugs.

What Are The New Cholesterol Guidelines?

The 2013 guidelines on cholesterol treatment can almost be reduced to answering a single question: Should this person be taking a statin drug, or not?

This question is answered by doing an assessment of the individual’s cardiovascular risk.  If the risk is considered “high,” a statin should be strongly recommended.  

There are four categories of “high risk” individuals for whom statin therapy ought to be used:

  1. People who have known cardiovascular disease due to atherosclerosis. Most of these people will have had a myocardial infarction (heart attack), angina, peripheral artery disease, or a stroke.
  2. People who have very high LDL cholesterol levels - greater than 189 mg/dL.  In most cases these are people with familial hypercholesterolemia.
  3. People with diabetes who are 40 to 75 years old. 
  4. People whose 10-year risk of developing cardiovascular disease due to atherosclerosis is estimated to be 7.5% or higher. (The NHLBI has provided this simple on-line tool to estimate your 10-year risk.) 

For the first two categories high-intensity statin therapy  - such as rosuvastatin (Crestor) 20 to 40 mg per day, or atorvastatin (Lipitor) 80 mg per day - is recommended for optimal risk reduction.  For the latter two categories, either high-intensity or moderate-intensity statin therapy can be used (moderate intensity being roughly half the high-intensity dose), depending on the judgment of the doctor and patient. 

Lifestyle modification to reduce risk, of course, is recommended for everyone, whatever their level of cardiovascular risk. Note, in particular, that it is at least possible for aggressive lifestyle changes to move some people out of category 3 altogether.

What Is Different About the New Cholesterol Guidelines, and What Do They Really Mean?

The most obvious difference between these new guidelines and the ones they replaced is that target cholesterol levels are no longer included in the treatment recommendations. And indeed, this seems to be the change being emphasized by most commentators on these new guidelines. 

But a closer examination will reveal that the 2013 guidelines represent a rather fundamental change in how cholesterol and its treatment are now viewed in relation to cardiovascular risk. 

Consider these important new ideas embodied in the new guidelines:

  • The new guidelines almost minimize the importance of cholesterol-lowering itself. In particular, the guidelines do not recommend adding to statins any of the non-statin cholesterol-lowering drugs - such as ezetimibe (Zetia, Vitorin), niacin, bile acid resins, or fibrates - in order to achieve some target cholesterol level.
  • Statins alone are recommended because, of the cholesterol-lowering drugs, the statin drugs alone have been shown to significantly reduce cardiovascular risk in high-risk patients.
  • While the cholesterol-lowering ability of statins may indeed have something to do with their risk-reducing effects, it now seems clear that the non-cholesterol-lowering features of statins are equally or even more important - which may be why these drugs are uniquely effective in lowering cardiovascular risk. In fact, one way to think of statins is: statins are risk-reducing drugs that also happen to lower LDL cholesterol levels.

The main idea behind these new guidelines, then, might be summarized this way:  High LDL cholesterol levels are a well-documented marker for an elevated risk of cardiovascular disease.  However, if the risk is high, the treatment ought to be aimed primarily at reducing the risk itself, rather than primarily at reducing cholesterol levels.  And statins are the only cholesterol therapy proven to significantly reduce elevated cardiovascular risk. 

What Is Likely To Change About These New Guidelines?

There is likely to be substantial controversy regarding which people fit into the fourth category - that is, which people are judged to have at least a 7.5% 10-year risk of having a potentially dangerous cardiovascular event.

The risk calculator provided by the NHLBI incorporates only those risk factors which have been “proven” in well-controlled clinical trials to contribute significantly to cardiovascular risk: age, LDL and HDL cholesterol levels, whether one is currently a smoker, and whether one has had elevated systolic blood pressure.

Two criticisms of this risk calculator are certain to be raised, and loudly. *

The first is that the emphasis on age places many people over the age of 60 at or very near the 7.5% cutoff.  And some will argue that a 7.5% cutoff itself is too liberal, and will say that a cutoff of 10% (a cutoff level that has been used in the past) would be more reasonable. So the new risk calculator will be criticized for adding “too many” people to the treatment list.

On the other hand, the risk calculator ignores several important risk factors that are widely agreed upon as being important, but which do not currently meet the panel's strict evidence-based standards.  These include a sedentary lifestyle, a strong family history of premature cardiovascular disease, a prior smoking history, CRP levels, and demonstrating the presence of calcium in the coronary arteries on a coronary artery calcium scan. Including any or all of these factors in a risk calculation would further increase the number of people for whom statins are recommended.

Whether you think the NHLBI risk calculator is too liberal or too conservative, odds are high that the inevitable debate will surely lead to changes in the future regarding which people ought to be included in the fourth category. 

In my view, however, whether a 7.5% or a 10% 10-year cardiac risk is considered unacceptable, and whether or not additional risk factors ought to be taken into account when estimating that risk, is something that can perhaps best be determined by you yourself and your own doctor. 

If I am in in categories 1, 2 or 3, my 10-year risk is extraordinarily high, and I should almost certainly opt for statin therapy, as long as I can tolerate it. But if I am close to the cutoff for category 4, I would like to decide for myself whether my level of cardiac risk is acceptable, and whether I want to take a statin drug to lower it, rather than to leave it to a government-convened panel (however expert and however well-meaning) to establish an arbitrary cutoff, which purports to make such an inherently individual decision for the entire population. 

*The predicted controversy arrived even sooner than I expected.

Sources:

Stone NJ, Robinson J, Lichtenstein AH, et al. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: A report of the American College of Cardiology/American Heart Association. J Am Coll Cardiol 2013.

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