Environmental and Genetic Factors That Influence Cardiovascular Disease in African Americans

BACKGROUND:

Heart disease and stroke remain the first and third leading killers of all Americans, with a disproportionate share of the burden borne by African Americans. Cardiovascular and total mortality are known to be higher among African Americans than among white Americans, but reasons for these differences remain unknown. In addition, well-documented declines in CVD and coronary disease mortality in the past three decades have not been shared equally between blacks and whites. Age-adjusted death rates were identical in both groups in 1980, but by 1994 the rate among African Americans was 14% higher than in whites. The race difference in magnitude of coronary heart disease (CHD) mortality is greater in women than men and higher in middle age, such that CHD deaths tend to occur in blacks about 5 years earlier than in whites. Excess cerebrovascular disease incidence and mortality in blacks are even greater than the differences noted in CHD.

Cardiovascular mortality rates in Mississippi, which are approximately 25% higher than the United States average, are the highest in the United States for all race-sex groups. Age-adjusted CVD mortality for African American women in Mississippi was 75% higher than in white women in 1994. The mortality for African American men was 47% higher than in white men.

Prevalence of hypertension is nearly 40% greater in African Americans than in whites and its sequelae are more frequent and severe. Evidence of target organ damage such as renal failure and left ventricular hypertrophy is more common in black than white hypertensives at comparable levels of blood pressure. Many risk factors are also more common in blacks, including diabetes, high serum lipoprotein levels [Lp(a)], and obesity (in women). Other risk factors, such as elevated total cholesterol, reduced high-density lipoprotein (HDL)-cholesterol, and heavy cigarette smoking, are more common in whites.

DESIGN NARRATIVE:

The Jackson Heart Study (JHS) initial examination, which began in the fall of 2000, included men and women ages 35 to 84, and took 3 years to complete. The coordinating center, located at Jackson State University, collects and analyzes data. The undergraduate training center at Tougaloo College offers coursework to students in public health and epidemiology, and provides practical experience in health research to prepare them for potential careers in these fields. The exam center at the University of Mississippi is responsible for recruiting participants and conducting examinations. JHS is uniquely positioned to answer key questions regarding the excess burden of CVD among African Americans and to address the critical shortage of minority investigators trained in epidemiology and prevention. These questions will be answered by incorporating state-of-the-art physiologic and epidemiologic methods in a stable population-based minority cohort, providing research experience, and building research capabilities at minority institutions. The Second Exam began in September 2005.