Background: Ambulatory blood pressure (BP) is considered more accurately reflect an individual's BP outside the physician's office and more representative of cumulative pressure exposure than is office BP. Therefore, the aims of this study were to determine the associations of cumulative burden of ambulatory BP and the risk of subclinical cardiovascular (CV) disease, and to identify the predictive values of longitudinal ambulatory BP in subclinical CV disease.
Methods: Ambulatory BP was measured up to 16 times over a 23-year period in 559 participants from childhood to young adulthood. Carotid intima-media thickness (IMT) and left ventricular mass index (LVMI) were measured in 404 and 390 participants respectively. Long-term cumulative BP burden were expressed by the area under the curve (AUC) and trajectory patterns (using latent class and growth mixture modeling). The associations of the cumulative burden of BP with IMT and LVMI were examined by using a linear regression model. We calculated the R2 statistic that is a measure of explained variation where higher values indicate more explained variation, and likelihood-ratio test was used to compare the goodness of fit of two models.
Results: We found that the cumulative burden of 24 hour, and daytime systolic BP were independently predictive of IMT (P<0.05); whereas cumulative burden of nighttime systolic BP were independently predictive of LVMI (P<0.05). Increased rate of growth in systolic BP was significantly associated with increased IMT and LVMI (P for trend <0.05). The AUC values of systolic BP have a steeper relationship with IMT and LVMI than baseline systolic BP. The cumulative burden of daytime systolic BP resulted in an approximate 20% (P<0.05) improvement in the prediction of IMT, and the trajectories of daytime systolic BP lead to a 2.65% (P=0.047) improvement in the prediction of LVIM. For diastolic BP, we only observed an association of cumulative burden of daytime diastolic BP and IMT (P<0.05).
Conclusions: Our results suggesting that the BP cumulative burden of ambulatory BP could substantially improve the prediction of subclinical CV disease.