Cross-Sectional Study of Arterial Stiffness in Adolescents with Down Syndrome.

Objectives To test whether youth with Down syndrome have aortic stiffness indices, as measured by pulse wave velocity (PWV), that differ from youth without Down syndrome and to compare reference-based age-adjusted (age-PWV-Z) and height-adjusted (Ht-PWV-Z) in youth with and without Down syndrome. Study design Cross-sectional study of PWV in 129 adolescents with Down syndrome and 97 youth of comparable age, sex, race/ethnicity, and body mass index (BMI). PWV, age-PWV-Z, and Ht-PWV-Z were compared. Regression models were developed to test for associations with PWV. Results Youth with Down syndrome and controls were comparable in BMI-Z (1.4 [-1.5 to 2.8] vs 1.2 [-2.0 to 2.8], P = .57) but not Ht-Z (-2.3 [-4.7 to 0.8] vs 0.4 [-2.0 to 2.6], P < .0001). PWV (m/s, 5.0 [3.1-7.9] vs 5.0 [3.6-8.0], P = .5) and mean arterial pressure (MAP, mm Hg) (78 [61-102] vs 74 [64-97], P = .09) were not different between groups. In adjusted analyses confined to Down syndrome, PWV was associated only with BMI, but not age, black race, or MAP (R-2 = 0.11). In contrast, BMI, age, black race, and MAP were all positively associated with and better explained PWV in controls (R-2 = 0.50). PWV was not associated with height in youth with or without Down syndrome. Although agePWV-Z was not different in Down syndrome (-0.36 [-2.93 to 3.49]) vs -0.15 [-2.32 to 3.22]), Ht-PWV-Z was greater in Down syndrome (-0.32 [-2.28 to 4.07] vs -0.08 [-2.64 to 2.64], P = .002), and Ht-PWV-Z was greater than age-PWV-Z in Down syndrome (P < .0001). Conclusions The lack of relationship of PWV, an independent predictor of adult cardiovascular events, with its traditional determinants including MAP suggests Down syndrome-specific phenomena may alter such relationships in this population. In youth with Down syndrome, Ht-adjusted PWV may overestimate aortic stiffness.