Newman's Notes: Rethink Cardio Risk Factors
Published: Oct 16, 2014 | Updated: Oct 17, 2014
Welcome to Newman's Notes, a regular column byDavid H. Newman, MD, the director of clinical research in the department of emergency medicine at Icahn School of Medicine at Mount Sinai. Newman, who also co-founded the NNT and authored "Hippocrates' Shadow: Secrets From the House of Medicine," reviews a variety of recently published studies. MedPage Todaylightly edits his comments, adding links and additional sources.
This week, Newman highlights a study from the New England Journal of Medicine, "Cardiovascular risk and events in seventeen low, middle, and high income countries."
This is a crazy study. They took 150,000 people and they interviewed them, they surveyed them, they got blood tests on almost all of them even though they were from 17 different countries. Researchers looked at these 150,000 people by income of the country.
For purposes of the study, the income of the country was considered high if you were in Canada, the United Arab Emirates, or Sweden. Those were the three high income countries. There were 10 middle income countries such as Brazil, China, Poland, and Iran. And then they had four low income countries: Zimbabwe, Pakistan, Bangladesh, and India.
Thus this study was intended as a sort of broad swath of countries that represented many income levels. It wasn't intended to be a perfect sampling of the entire world but a definite sampling of low and middle and high income countries.
And the reason researchers did this was because we know that cardiovascular events like heart attacks and strokes, dying and dropping dead, sudden cardiac death, those are problems in high income countries that we've been tracking for years but they've been very poorly tracked in the low and middle income countries, particularly the low income countries.
And it's never been totally clear -- at least until this point it hasn't been totally clear -- exactly how many people are having major cardiovascular events in the low and middle income countries compared with the high income countries.
What They Did
The researchers surveyed and drew blood on all of these different people. Then they tracked them for roughly 4 to 5 years. And on a per person, per time basis, they reported how many people had:
- Newly diagnosed hypertension
- Heart attacks
- Atrial fibrillation
- Strokes
- Any kind of event that led to hospitalization
- Death related to and unrelated to cardiovascular events
Tracking all of those things in the low and the middle and the high income countries led them to some really fascinating numbers -- numbers that I think were very unexpected for a lot of public health research.
Researchers used what's called the INTERHEART Risk Score, which is a validated method to evaluate people's risk burden for cardio events and assign a metric for comparison.
What They Found
This INTERHEART score was highest in high income countries (12.89; 95% CI 12.79-12.98), and declined in middle income countries (10.47; 95% CI 10.43-10.50) and was least still among lowest income nations (8.28; 95% CI 8.23-8.34); (P<0.001).
They found that if you were in a high income country, you were actually a little bit more likely than people in the middle and the low income country to have what they call the nonmajor medical cardiovascular event. And that meant something like a hospitalization for an arrhythmia. Or a hospitalization that was due to a hypertension problem.
On the other hand, they had tremendously more events in the low income folks that were fatal. If you are in a low income country, you're almost four times as likely to die during that 4 to 5 years of follow-up than if you were in a high income country. And you were four times as likely to die of a cardiovascular event if you were in a low income country. You were two to three times more likely to have a myocardial infarction if you were in a low income country.
Now on the face of it, it actually sounds maybe not that surprising that the low income countries might have a higher rate of major events. But if you go back and you look in this study -- at the risk factor burden among the low income folks and then the risk factor burden among the middle income and high income people -- what you find is that people in the high income countries had the highest risk factor burden.
For example, this means they had higher cholesterol. In fact, almost half of the people in high income countries had high cholesterol. The hypertension and the diabetes rates were also higher in the high income countries. The rates of severe stressors, self-reported stressors were higher in the high income countries.
The risk factor burden and the overall risk score for the people in the high income countries would have predicted that more of the people in the high income countries should have had heart attacks, should have had strokes, and should have died. But as a matter of fact, it turned out that quite the opposite was true. It was the low income countries that people were dying of heart attacks, dying of strokes, and having major events at a much higher rate.
It's Not the Healthcare System
What does this tell us? Well, it tells us a number of things that we really need to tune in to in order to address the public health issues that we need to fix to make people healthier in the U.S., but also to make people healthier in the low income countries.
It probably means first of all that by itself risk factor burden is not a wonderful predictor of who is or is not going to have a heart attack or a stroke or die. All of the things that we have known for years are probably much better predictors, like genetics and like socioeconomics and like environment. All of those things are probably much more robust predictors of who's going to die and who's going to have a heart attack.
Now, in the high income countries we have access to great healthcare compared with low income countries. And yet it didn't save us. Having access to all that healthcare did not save us.
You're going to see a whole lot of people talking about how the reason that high income people weren't dying as often was because they had access to wonderful heathcare; I'm here to tell you that's wrong. There's no way, that's not it, man.
What's going on is that the genetics and the socioeconomics and the fact that there is no public health infrastructure in middle and particularly low income countries. It means that there is no clean water and irrigation and access to any kind of minimal primary care. It's not about our highfalutin drugs, it's not about our cholesterol lowering, it's not about all that. It's about something much more fundamental and basic.
The low income countries need access to all that public health infrastructure. They need money, they need all kinds of public health infrastructure that's based on having money. And the high income countries -- we need something else. We need to start looking at exactly what we're doing to try and modify our own risks. And maybe start thinking about something other than the risk factor burdens the way we currently define them.
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