Longitudinal perspective on the conundrum of central arterial stiffness, blood pressure, and aging

Abstract

The age-associated increase in arterial stiffness has long been considered to parallel or to cause the age-associated increase in blood pressure (BP). Yet, the rates at which pulse wave velocity (PWV), a measure of arterial stiffness, and BP trajectories change over time within individuals who differ by age and sex have not been assessed and compared. This study determined the evolution of BP and aortic PWV trajectories during a 9.4-year follow-up in >4000 community-dwelling men and women of 20 to 100 years of age at entry into the SardiNIA Study. Linear mixed effects model analyses revealed that PWV accelerates with time during the observation period, at about the same rate over the entire age range in both men and women. In men, the longitudinal rate at which BP changed over time, however, did not generally parallel that of PWV acceleration: at ages>40 years the rates of change in systolic BP (SBP) and pulse pressure (PP) increase plateaued and then declined so that SBP, itself, also declined at older ages, whereas PP plateaued. In women, SBP, diastolic BP, and mean BP increased at constant rates across all ages, producing an increasing rate of increase in PP. Therefore, increased aortic stiffness is implicated in the age-associated increase in SBP and PP. These findings indicate that PWV is not a surrogate for BP and that arterial properties other than arterial wall stiffness that vary by age and sex also modulate the BP trajectories during aging and lead to the dissociation of PWV, PP, and SBP trajectories in men.

Keywords: aging; arteries; blood pressure; longitudinal studies; pulse wave analysis; sex.

Figure 1

Longitudinal trajectories and 95% confidence bands in PWV in men (panel A) and women (panel B) and five year longitudinal rates of change in PWV with 95% confidence intervals (panel C) from mixed-effects models in men and women of different ages at entry into the study. Note that rates of change at all ages are positive. Since the data becomes more sparse with advancing age (Supplement Figure S1 and Table S1), the longitudinal plots of the modelled data are only constructed for entry ages up to 75 years. Note: The equation to predict ln(PWV) for a man is: ln(PWV) = 1.3671 + 0.0116 × (Entry Age) + 0.008744 × Time. The predicted value of PWV is obtained as e^ln(PWV). Predicted values for PWV in women or for other variables can be obtained in a similar fashion by inserting appropriate values of the explanatory variables into the relevant equations.

Figure 2

Longitudinal trajectories and 95% confidence bands in PP, SBP, and DBP from mixed-effects models in men (Panels A, C, and E) and women (Panel B, D, and F) of different ages at entry into the study.

Figure 3

Five year longitudinal rates of change in SBP (panel A), DBP (panel B), PP (panel C) and MBP (panel D) with 95% confidence intervals from mixed-effects models in men and women of different ages at entry into the study. Note that beyond 50 years the rates of change in the BPs in men become negative, indicating a fall in the absolute pressure. Note that rates above zero imply increases in the parameter.

Figure 4

Combined data from Figures 1C and 3 to compare five year longitudinal rates of change in PWV, PP, SBP, DBP, and MBP from mixed-effects models in men (panel A) and women (panel B) of different ages at entry into the study. Note, the general dissociation between the rate at which the BPs and PWV change in men.