CV Risk Calculator and Lipid Guidelines: The Future Is Bright

Neil J. Stone, MD


April 24, 2014

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Positive Buzz for REGARDS

Hello. I am Dr. Neil Stone. I am here in Washington, DC, at the American College of Cardiology (ACC) meeting to talk about the new 2013 ACC/American Heart Association (AHA) guidelines on the management of cholesterol to reduce atherosclerotic cardiovascular risk, heart attack, and stroke.

I want to talk about some of the positive buzz that I have heard at these meetings. Yesterday was the presentation[1] and then publication in JAMA[2] of the REGARDS trial, a large-scale, community-based study that looked at how accurate and discriminatory the risk estimator was. This trial showed that the risk estimator had very good calibration or accuracy. It also showed that the risk calculator discriminated, meaning that it rank-ordered the people in the trial from high to low.

This was welcome news. The risk estimator had been internally and externally validated before it was released, but now a published study shows that in the population for which it was meant (the US population), it performs well.

In addition, I have attended sessions in which the new guidelines have been discussed. We have 4 statin benefit groups: (1) those who have had a heart attack or stroke (so-called secondary prevention); (2) those with low-density lipoprotein cholesterol (LDL-C) levels ≥ 190 mg/dL (more of a primary nature, usually genetic); (3) people with diabetes aged 40-75 years over a wide range of LDL-C values; and (4) the primary prevention group.

Moving Beyond the Headlines

Some of the discussion was focused on the primary prevention group. This is a group about which the headlines have stated that we treat anyone with an estimated risk of 7.5% or more. That is not actually what the guidelines stated.

The guidelines stated that the risk estimation should be done in primary prevention because an awful lot of risk is left on the table if you only treat for secondary prevention, and we should specifically look at those who have an increased risk for a heart attack or stroke. We said that even though the careful analyses done by the panel showed benefit from statin therapy in this group down to a risk level of 5%, we chose 7.5% as the cutoff for a clinician/patient discussion.

We found that discussion to be so important that we included it in the "What's New" table. It is seen in Figure 4 of the document and in detail in the text.

We called our guidelines "patient-centered" because during that discussion, there is an opportunity to discuss the benefits of lifestyle change; to correct other risk factors, such as blood pressure and smoking; and to look at patient characteristics that tell you whether the patient would benefit from a statin or would have a negative effect -- in other words, an adverse effect or a drug/drug interaction.

For example, in a patient who walks in with severe muscle problems, you might not want to start a statin for fear that it could upset the apple cart. But it allows the clinician to use the evidence, and to use informed patient judgment, to make the decision about statin therapy in primary prevention. Estimates of how many people are treated by our guideline are only estimates; they don't actually determine who is treated, because patient characteristics and patient preferences are very important in that decision.

We also wanted people to know that there were other factors that we used to adjudicate who receives a statin, and these include several patient characteristics. For young people, the important characteristics are an LDL-C level > 160 mg/dL, an elevated lifetime risk, or a family history of premature coronary heart disease or atherosclerotic cardiovascular disease. In other words, a patient with an LDL-C level of 180 mg/dL and a family history, who is aged 35 or 41 years and doesn't have an elevated short-term risk, would definitely be considered for treatment per the guidelines.

Moreover, we have factors that can be useful for older patients. Some people have wondered about the patient who qualifies primarily on the basis of age (65 years for a man or 71 years for a woman). Although this patient is at elevated risk because the arteries have seen all of those risk factors over a long period, we say that a coronary artery calcium score, a high-sensitivity C-reactive protein level, or an ankle/brachial index could be used if further information was needed in the face of an uncertain risk decision.

Guidelines Are Just Guidelines

But standing alone, the guidelines are just guidelines. They are designed to inform clinical judgment, not replace it. And I feel very happy that I am beginning to see articles that now acknowledge exactly what an important role the guidelines can play in cholesterol management.

In addition, we were encouraged by the fact that not only did the cholesterol treatment trial (the per-person meta-analysis) show a benefit in primary prevention as well as secondary prevention in terms of total mortality, but the most recent Cochrane analysis from 2013[3] also showed a benefit of statin therapy in primary prevention on total mortality.

Taken as a whole, we feel strongly about the recommendation for statin therapy in those who benefit the most. That is why we encourage the risk discussion to best decide on statin therapy in primary prevention.

In closing, I encourage everyone to read the synopsis in Annals of Internal Medicine [4] about the cholesterol guidelines, and to download the risk estimator from the CardioSource Website. I think you will find how beautifully you can be informed about what the guidelines say. Thanks very much.


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