Landmark Heart Study Pioneers the Science of Health Disparities

Feature Story
physician checking woman's blood pressure

For the past 30 years, Wanda Johnson and more than a thousand Kaiser Permanente members have participated in a pioneering national study of race and gender disparities in heart health, called the Coronary Artery Risk Development in Young Adults (CARDIA) study.

CARDIA was initiated by the National Heart, Lung, and Blood Institute in 1985. Unlike other heart studies, its participants were young, between 18 and 30 years old, and included blacks and whites and men and women.

“There were a lot of studies at that time on middle-aged, Caucasian men, and to be a young, African-American female – it just seemed interesting,” said Johnson, who was 27 years old when she enrolled in CARDIA. Now 57, she recently returned to Kaiser Permanente’s Oakland Medical Center for her ninth round of CARDIA tests.

Loyal study participants such as Johnson have provided a wealth of information on how blood pressure, cholesterol and weight, and lifestyle factors such as exercise and smoking, affect heart health.

Nationally, the CARDIA study is following more than 5,000 participants in Birmingham, Chicago, Minneapolis and Oakland. Anonymous data pooled from the four cooperating study locations has resulted in more than 600 papers and 700 presentations, as well as dozens of related studies.

Lifestyle risk factors, disparities identified

CARDIA principal investigator Stephen Sidney, MD, MPH, senior research scientist and director of research clinics with the Northern California Kaiser Permanente Division of Research, said that some the study’s most important findings concern the relationship between lifestyle and heart health.

“We documented that young people with high blood pressure have higher rates of coronary artery calcification, a condition that increases the risk of heart attacks,” Dr. Sidney said. “Lifestyle behaviors such as cigarette smoking and physical inactivity also increased the rate of calcification.”

The study’s findings regarding disparities between black and white participants are also of particular importance, Dr. Sidney said. “During the study’s first 20 years, 26 black participants were diagnosed with heart failure and only one white participant.”

Due to his career-long involvement with CARDIA, Dr. Sidney has become passionate about finding evidence-based approaches to controlling blood pressure 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,” he noted.

Seeking to find solutions for disparities that the CARDIA study helped to identify, Dr. Sidney and the Division of Research received new funding several years ago for a major Oakland-based intervention study to reduce stroke and heart disease in the black community.

“Through the CARDIA study and our efforts to develop innovative lifestyle interventions beginning early in life, supplemented with the strategic use of medication when needed, we have a chance to develop evidence-based practices aimed at eliminating disparities,” Dr. Sidney said.

Kaiser Permanente is widely recognized as a leader in hypertension control. In fact, the U.S. Department of Health and Human Services has designated three of the organization’s regions as Million Hearts Control Champions: Northern California, Southern California and Colorado. In addition, in 2014, Kaiser Permanente had achieved nearly 90 percent hypertension control rates across the regions it serves, which is well above the national average of 52 percent.