Study pioneers the science of health disparities—and launches quest to solve big problems in health care.
By Janet Byron
Stephen Sidney, MD, MPH, has spent a good portion of his 30-year career with the Northern California Kaiser Permanente Division of Research (DOR) as principal investigator for the Coronary Artery Risk Development in Young Adults (CARDIA) study.
Funded by the National Heart, Lung, and Blood Institute, the landmark study has followed more than 5,000 participants in Birmingham, Chicago, Minneapolis, and Kaiser Permanente’s Oakland Medical Center since 1985. Anonymous CARDIA data is pooled from the four cooperating study locations.
Dr. Sidney says he is obsessive about daily running; he has taken the multitude of CARDIA tests alongside participants since the study began.
When CARDIA began, most cardiac studies involved middle-aged white men. CARDIA participants were between 18 and 30 years old, and they included blacks and whites, and men and women. Participants were assessed every 2 to 3 years until 1995, then every 5 years through 2010—providing a wealth of data on how blood pressure, cholesterol and weight, and lifestyle factors such as exercise and smoking affect heart health. In return, participants received information that included blood test results and other measurements. CARDIA has resulted in more than 500 papers and 700 presentations, as well as dozens of related studies. Dr. Sidney spoke with Janet Byron of the DOR about CARDIA’s impact.
Which of the many CARDIA findings have had the broadest impact on the science of cardiovascular health?
Many of the major CARDIA findings concern lifestyle. We documented that young people with high blood pressure have higher rates of coronary artery calcification (CAC), a condition that increases the risk of heart attacks. Lifestyle behaviors such as cigarette smoking and physical inactivity also increased the rate of CAC.
Which data are you looking forward to analyzing after the next evaluation, in 2015-2016?
We plan to repeat an ultrasound of the heart, called electrocardiography, which provides detailed information about the heart’s structure and function. We’ll be able to see changes developing, and it will give us lots of information about the risk factors for heart failure. While heart attacks and strokes have been declining, heart failure—the heart’s inability to pump blood adequately to meet the needs of the body—is a huge problem.
We’ll also use brain MRIs to examine issues of cognitive function in middle age. It makes sense—decreased blood supply to the brain, due to fatty deposits and calcification of blood vessels, can affect both brain structure and cognitive function. We’ll be getting a baseline for understanding cognitive decline from the now middle-aged CARDIA participants all the way into older age.
Where do you see CARDIA headed?
We hope to continue following the subjects periodically for as long as we can get funding. As participants get older, will be able to describe the development of heart disease from young adulthood onward, and understand the relationships among the physiological, behavioral, psychosocial, and environmental factors that cause these diseases. In doing so, we can learn how to prevent cardiovascular disease, the leading cause of mortality in the United States.
How has CARDIA affected your own research agenda?
Due to my involvement with CARDIA, I’ve become passionate about the issue of hypertension in young black people. Despite the tremendous success that we’ve had in leading the way with hypertension control at Kaiser Permanente, the disparity between blacks and whites in cardiovascular risk factors and outcomes is still about 5 percent, and hypertension control rates are lower for young black men than young black women. DOR recently received federal funding for an exciting intervention study to reduce stroke and heart disease in the black community. I’m working to get that message out and develop an action plan.