Who's at Risk? A Defense of the CV Risk Calculator

Sidney C Smith Jr, MD; Shelley Wood


November 20, 2013

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Shelly Wood: Hi. I am Shelly Wood, the managing editor for heartwire , and my guest is Dr Sidney Smith, and our topic today, as for the whole last week, is the new AHA/ACC guidelines. Now today, we had some excitement with an article that came out in the New York Times suggesting that maybe the risk calculator used as the basis for these guidelines perhaps was not as accurate or was sweeping too many people into the risk category than we wanted. We have had quite a reaction by the rest of the media here at the AHA meeting, but let's hear from you. Are you confident that the work that you did in so many ways with these guidelines is actually going to capture the right people in terms of who needs more treatment and who doesn't?

Sidney C Smith, Jr, MD: Well, I think these guidelines are going to make a big difference. I am very comfortable with what we have done. The first thing we found is that there is really no evidence from randomized control trials to support the use of [a] target, so now we are—so it is a big message, and we have four groups out there—patients with established disease, patients with [familial hypercholesteremia] FH that have inherited elevation of the cholesterol, patients with diabetes, and patients at risk for primary prevention—intensive statin if you have known cardiovascular disease, if you have FH, if you have diabetes, and a risk of about 7.5%, and then that leads us to what about the rest of the population? What about primary prevention? And as we got into the development of a risk instrument there are a couple of things that we did. The first was that we expanded the outcomes from purely cardiac to heart and stroke. The second is that recognizing the rich, the beautiful mosaic of ethnicity that is evolving in North America now, we had to have more than Framingham. So we have got African American. We really have expanded the risk calculator so that that [an] African American male with hypertension who is potentially going to have a stroke is a candidate for treatment. That woman who is 60 who is a smoker and has hypertension won't go ignored. And so if you begin to look at a cut point for treatment as we looked at the randomized trials, it was clear—and this has been further substantiated by the Oxford group—that if you look at the primary-prevention trials, the patients being treated there are at much lower risk than would have been called for in ATP 3.

Ms Wood: So you get rid of goals, you target people who would benefit the most from intensive therapy.

Dr Smith: Expand the risk in primary prevention is the next thing, and that is where the question comes up, and what we looked at was that actually benefit would occur down to a risk with a new risk calculator to 7.5% and maybe as low as 5%, and that was consistent with what we saw in the randomized trials. So the numbers of patients come up. You look at ATP 3, you would predict roughly 15 million patients should be treated. If you look at our recommendations, it would be maybe 31 million, but wait a minute, we know in the United States, there are roughly 100 million people between the age of 40 and 75. We know one out of three deaths are cardiac or stroke and we know 60% of people in their lifetime will have a heart attack or stroke.

Ms Wood: So that increase, which is about double, you think is probably justified?

Dr Smith: Well, we are saying what is wrong with treating one in three patients in a society where one out of three patients is dying from cardiovascular disease and 60% are having events?

Ms Wood: One of the criticisms here, though, is that you have developed this CV risk calculator, and it wasn't published. It has been published now, but it wasn't tested widely in the academic community before it was announced this is what should be used. Now, did you test it internally in ways that people can't quibble with?

Dr Smith: Yeah, it is called validation, and it was validated in different cohorts, but it is very important prospectively to validate any risk-assessment tool, and so what has come up at the meeting has been a suggestion by another investigator that gee, when he looks at his cohorts of patients that the risk predictor may overpredict, so my response to that is I love the evidence. Bring it on. Let's see. But we really need more than what has been brought forward. We need to know a lot more about those cohorts to see—I mean, were the patients in the cohorts, did they have their blood pressure measured? Did they just report themselves as having hypertension? How many of them might have been on statins? We don't know. So we will look at that.

Ms Wood: So you have a prominent person like Steve Nissen telling, telling the New York Times we should pause. A lot of fanfare went into the release of these guidelines. He is saying too soon. Press the pause button. Let's just make sure we are capturing the right people with this. Now are you confident that the risk calculator as it is now, if people start initiating treatment or making treatment changes based on it, that the right people are going to get treatment or not?

Dr Smith: I think we are going to do a good job, but again, I want to say that this risk calculator is not, go to the computer, plug in your numbers, and go to the drugstore and grab your bottle of statins. You sit down with your physician and have a discussion about this. Now it may be that you're 63 and you are not sure about—you have a 7.8% risk. You maybe want to look at coronary calcium or you may want to look at [C-reactive protein] CRP. If that is a total zero coronary calcium, negative CRP, you may say I'd rather not do this. But all of us who work in cath labs, who work in emergency rooms, see patients come in where those LDLs don't look that bad. People say couldn't something have been done? What we are seeing the [randomized clinical trials] RCTs is evidence that lower-risk patients benefit from treatment. Now, the new suggestions came along as these guidelines were being released, and sure, we are going to look at it. We do that with all of our guidelines. If we have a new RCT, we will sit down and look at it, but we don't stop. I don't think we are going to be doing a great deal of harm by moving forward with these predictions, because the major overruns are in the high-risk people that you are going to treat anyway or in the very low that you are not. There is some disparity between this cohort that was raised, the group of patients and the risk calculator, but we still don't know how well they would meet the inclusion, exclusion criteria that were put before us through the Institute of Medicine in terms of developing a model, so I think we need more information before we just totally stop an effort to prevent.

Ms Wood: People have waited a long time for this, so I think no one is going to want to stop. I am a little bit worried that as we see these big articles in the newspapers, a lot of press will come out of the AHA meeting. Are you worried that the public perception of these guidelines will be that this is flawed in some way, and I don't know if I can trust my doctor? Is my doctor relying too heavily on these guidelines, 'cause I have heard that maybe they are overtreating people. What will public fallout be from this type of controversy?

Dr Smith: Well, I hope that it will raise the public's awareness of risk, of know your risk. If there is one message I would get out it is think seriously about the fact that you could have a heart attack or a stroke and start thinking seriously about what those risk factors are and correct them. I don't think we are at a point where we should be having statins in the water. I am not at that point. I do think that patients at lower risk who have been previously treated could benefit from lower-dose statins, and we will continue to work and see. We will try to make it perfect, and if there are data out there that might be helpful, we will be careful to look at them. Bring it on. I agree. Have everybody at the table. But I want to be sure that we really are acting on data that will help.

Ms Wood: That is valid, and I can't help but think that this is being interpreted as oh, the CV risk calculator may be flawed. Everyone is going to be statins. I would point out that there were four documents that came out that day. There was the CV risk calculation document. There were the lipid cholesterol guidelines, but there were the obesity guidelines and lifestyle guidelines, and I have to say I don't hear those talked about as much, and presumably you would like people who are considering their risk to be thinking about all four of those documents.

Dr Smith: Shelly, I couldn't have said it better.

Ms Wood: I wrote one of them. I wrote the lifestyle one.

Dr Smith: Really, really important. Lifestyle, obesity, very important in our society, and if we could only do a good job there we could cut down I think even more on the amount of statins that might be helpful.

Ms Wood: Right. Well, we have only talked about the documents in the context of the US, where they were developed in collaboration with the [National Heart, Lung, and Blood Institute] NHLBI, but this is a global issue of course, and that is one of your interests.

Dr Smith: It is a deep interest, and I think I am very concerned about the relative lack of data in the 80% of the world with developing economies where the majority of these events are occurring. We need more randomized trials in those parts of the world so that we have a good database. There may be differences in bleeding. We know there is a difference in intracerebral hemorrhage in Asia, for instance. It may be that lower-dose statins are better and more comparable [in] efficacy. So I think if I could have at least one dream in terms of guidelines, it would be a broader evidence base worldwide.

Ms Wood: Incorporating some of those other populations. Well, maybe we can talk about this in a couple of years if some of those studies happen, and if not, we will find other things to talk about, I am sure.

Dr Smith: You know we have a World Congress coming up in Melbourne in May of 2014, and we will put as much of that on the table as we can, so...

Ms Wood: Great. Well, will be there covering that news, so we look forward to it.

Dr Smith: I'll look forward to that.

Ms Wood: Thanks so much for taking the time to talk to me today.

Dr Smith: Thank you.


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