Blood Pressure in Young Blacks and Whites: Relevance of Obesity and Lifestyle Factors in Determining Differences

BACKGROUND: Middle-aged black men and women have higher blood pressure, on average, than whites. However, this pattern is inconsistent in children and adolescents. This study explores how differences in lifestyle factors in young adulthood may influence blood pressure patterns in the two races. METHODS AND RESULTS: The Coronary Artery Risk Development in Young Adults (CARDIA) study is an ongoing collaborative investigation of lifestyle and the evolution of cardiovascular disease risk factors in a random sample of young adults ages 18 to 30 years at baseline (1985 to 1986). Data from four examinations over 7 years were analyzed with the use of a method that simultaneously examined cross-sectional and longitudinal relationships of lifestyle factors and blood pressure. This study included 1154 black women, 853 black men, 1126 white women, and 1013 white men. Blacks had higher systolic blood pressure and diastolic blood pressure than whites at every examination. Racial differences were much greater in women than in men and increased over time. Within each sex-race group, average diastolic blood pressure over four examinations was positively associated with baseline age, body mass index, and alcohol intake and negatively associated with physical activity, cigarette use, and intake of potassium and protein. Longitudinal change in diastolic blood pressure was positively associated with changes in body mass index and alcohol intake. After adjustment for obesity and other lifestyle factors, black-white diastolic blood pressure differences were reduced substantially: 21% to 75% for men and 49% to 129% for women. Results for systolic blood pressure were similar. CONCLUSIONS: Differences in obesity and other lifestyle factors in young adults largely explain the higher baseline blood pressure and greater increase over time of blacks relative to whites.