Anyone who has seen a doctor recently knows the major culprits of heart disease high cholesterol, high blood pressure, smoking, too little exercise. For years, physicians have been warning their patients about these risk factors for heart attack and stroke. But with the explosion of research on the genetic drivers of disease, a group of experts at Brigham and Women's Hospital in Boston wondered how these tried and true markers of heart problems would stack up against the predictive power of the latest genomic science.
What they found came as a bit of a surprise. It turns out that the simpler measures blood pressure, cholesterol and even family history of the disease could predict just as accurately as sophisticated genetic screens who was at highest risk of heart problems in a 12-year follow-up period.
"The genetic screen didn't really add predictive value to any of our current models," says Nina Paynter, an instructor in the division of preventive medicine at Brigham.
She and her colleagues assessed whether the predictive capability of two popular screening tools that heart experts currently use known as the Framingham risk score and the Reynolds score could be improved by adding information from two genetic screens that her team constructed by scouring the literature for genes that had been linked to heart disease.
The Framingham score is a decades-old tool established by a landmark study that began in 1948 (and continues today), which identified seven major predictors of heart disease older age, diabetes, smoking, high blood pressure, high total cholesterol, low HDL cholesterol and a BMI in the overweight or obese range. The Reynolds score is a more recent screen that uses the Framingham risk factors as a base and adds another, inflammation, which in recent studies has been linked to an increased risk of heart disease.
The two genetic screens included one set of 101 gene changes that have been linked to heart disease as well as to factors that can contribute to heart disease, such as high blood pressure, diabetes and high cholesterol. The second genetic screen was a leaner library of 12 genetic changes for which published studies have found a definitive link to heart disease only.
Among the more than 19,000 women followed in the study, published Tuesday, Feb. 16, in the Journal of the American Medical Assocation, those deemed by the genetic screen to be in the lowest risk group had a 3% risk of developing heart disease, while those in the highest risk group had a 3.7% risk just barely significant and, by Paynter's admission, not a large difference at all. "Adding the risk scores really didn't add anything," she says.
But that doesn't necessarily mean that genes aren't playing any role in heart disease. In fact, given that family history is significantly predictive of an individual's heart-disease risk, genes are likely a very important component of that risk profile. It's just that our current screening tools are already capturing much of this genetic contribution. "This study reflects the fact that genetic influences can be controlled through lifestyle," says Dr. Lori Mosca, director of preventive cardiology at New York Presbyterian Hospital.
In other words, many of the factors that contribute to heart disease are within most people's power to control by keeping blood pressure and cholesterol low, staying slim and not smoking. "This is good news for patients, because if people believe their risk is driven by genetic factors, I think they are less likely to be motivated to adopt a healthy lifestyle," says Mosca. "We know what causes heart disease, for the most part." And we can't blame our genes for all of it.