LONGITUDINAL ASSESSMENT OF BLOOD PRESSURES IN BLACK-AND-WHITE CHILDREN

The prevalence of hypertension is greater for blacks than whites. Whet her black children have higher blood pressure than white children is l ess clear. We investigated this issue through a prospective longitudin al assessment of blood pressure in 345 white children and 164 black ch ildren. Each child had his or her blood pressure measured every 6 mont hs for 2 to 5.5 years. The means for systolic and diastolic blood pres sures for each individual were calculated, and the rate of change in b lood pressure over time for each subject was estimated. The mean blood pressure and the mean rate were compared between gender-specific blac k and white groups. For both boys and girls, the mean systolic blood p ressure was 2 mm Hg higher in black children than white children (P=.0 008). Boys had a higher systolic blood pressure than girls (P=.0048). The mean diastolic blood pressure was 1.5 mm Hg higher in black childr en than in white children (P=.0270); no significant gender difference in diastolic blood pressure was observed. Age, weight, height, and bod y mass index were highly correlated with blood pressure. When accounti ng for these variables, for girls the racial difference in systolic bl ood pressure remained significant, whereas the difference in diastolic blood pressure in boys and girls was no longer significant. The rate of increase in blood pressure over time was significantly greater in b lacks than whites: for systolic blood pressure, P=.0002, and for diast olic blood pressure, P=.009. There was no sex difference in rate of ch ange in systolic blood pressure, whereas girls showed a greater increa se in diastolic blood pressure over time than boys (P=.0131). In summa ry, the average blood pressure for black children was higher than in w hite children, and the blood pressure increased at a faster rate in bl acks compared with whites. The findings suggest that mechanisms that p redispose blacks to hypertension may be functioning in childhood.