Comparing the associations of clinic vs. ambulatory blood pressure with subclinical organ damage in young healthy adults: the African-PREDICT study.

Raised blood pressure (BP) causes pathophysiological cardiovascular changes resulting in target organ damage. Although ambulatory and central BP relate more strongly to outcomes than clinical brachial BP in the elderly population, it is unknown which measure of BP is most strongly associated with markers of organ damage in younger populations. We compared the strength of associations between different BPs and measures of subclinical organ damage and investigated whether ethnic differences exist between these associations. The design was a cross-sectional analysis of the African-PREDICT study, including young black and white men and women (aged 20-30, N = 1202). We obtained clinic, ambulatory, and central BP readings, as well as measures of subclinical organ damage: central retinal arteriolar equivalent (CRAE) from fundus images, echocardiography to determine left ventricular mass index (LVMi), carotid intima media thickness (CIMT), carotid-femoral pulse wave velocity (PWV), and albumin-to-creatinine ratio (ACR) determined from spot urine samples. Overall, weak correlations were evident between CIMT, ACR, and BP, whereas CRAE, LVMi, and PWV correlated strongly with BP. In the total group, clinic brachial BP had stronger associations with CRAE, LVMi, and PWV (all p < 0.001) than ambulatory and central BP. Although the ethnic groups showed similar correlations between CRAE, LVMi, CIMT, and the various BPs, PWV correlated more strongly with ambulatory systolic BP (p < 0.001) in white participants. In young healthy adults, clinic brachial BP correlated more strongly with measures of early target organ damage than central or ambulatory BP. No differences were observed between correlations of BP and measures of target organ damage in the two ethnic groups.