More than half of all cardiovascular diseases worldwide have been found to be directly connected to five classic cardiovascular disease risk factors, with high blood pressure being the most significant factor related to heart attacks and strokes. Dr. Christie Ballantyne, professor of medicine, and Dr. Vijay Nambi, associate professor of medicine, both with Baylor College of Medicine, are co-authors along with a large group of scientists who make up the Global Cardiovascular Risk Consortium who recently published these findings in the New England Journal of Medicine.
The consortium, under the leadership of the University of Heart & Vascular Center of the Medical Center of Hamburg-Eppendorf and the German Center for Cardiovascular Research, used data from 112 studies consisting of 1.5 million people from 34 different countries.
The group reports that two conclusions can be made from these findings: The first, that more than half of all heart attacks and strokes can be prevented by understanding, treating or preventing the five classic risk factors: weight, high blood pressure, high cholesterol, smoking and diabetes. The second, that the other half of heart attacks and strokes cannot be explained with these risk factors and more work and research is needed to find additional causes.
“With lifestyle changes and medications, we have all the tools necessary to reduce heart attacks and strokes by over half in middle aged people, and I believe that the reduction could be much greater if we began earlier in life,” said Ballantyne, who also is chief of cardiovascular research at Baylor.
An important aspect of the study involved understanding the global distribution of risk factors, how they affect those from each region in the study and how this information can be used to find targeted preventative measures. Eight geographical regions were examined: North America, Latin America, Western Europe, Eastern Europe and Russia, North Africa and the Middle East, Sub-Saharan Africa, Asia and Australia.
Researchers saw different risk factors directly associated with heart attack and stroke in each region. In Latin America, being overweight was a high risk factor while high blood pressure and cholesterol was seen in Europe. Smoking was a high risk factor in Latin America and Eastern Europe and diabetes was affecting more people in North Africa and in the Middle East. However, across regions, high blood pressure and high cholesterol showed a linear connection to the occurrence of cardiovascular diseases.
All five risk factors combined amount to 57.2% of women’s cardiovascular risk and to 52.6% of men’s. Thus, a substantial share of cardiovascular risk remains unexplained. In comparison, the five risk factors merely account for about 20% of the risk of overall mortality.
“While intensifying treatment of these traditional risk factors has continued to show additional value, current research focuses on how to identify and mitigate the ‘residual risk.’” said Nambi, who also is with the Michael E. DeBakey VA Medical Center. “The role of risk factors such as inflammation and lipid markers such as lipoprotein (a) have been identified and ways to manage these are currently being investigated. Advances in genomics, proteomics and metabolomics continues to help us better understand the pathophysiology of cardiovascular disease.”
Other interesting findings showed that very high and very low cholesterol levels increased overall mortality, and the significance of all risk factors decreases with age. For example, high blood pressure is more damaging to a 40-year-old than an 80-year-old.
For a full list of consortium members, associated institutions and financial disclosures see the full publication. Lead author on the study is Dr. Christina Magnussen, the University Heart & Vascular Center of the Medical Center Hamburg-Eppendorf. Ballantyne and Nambi are both investigators in the Atherosclerosis Risk in Communities study, a long-term population study investigating the causes of atherosclerosis and its clinical outcomes, and variation in cardiovascular risk factors, medical care, and disease by race, gender, location and date. Data from the ARIC study was used for the current NEJM publication.