Table 2.

Association of Age, Sex, and Race with Carotid Artery Distensibility Coefficient and Diameter

	Difference in DC (2*slope) mm Hg−1	% Larger carotid diameter (intercept)
Covariate	Beta coefficients (95% CI)
Sex (male vs. female) at 65 years of age	8.24 (0.62-15.8)×10−5	4.83 (3.99-5.69)%
Age (difference per year among females)	−5.04 (−5.38-−4.70)×10−5	0.24 (0.20-0.28)%
Difference in age-associated slope between men and women	7.14 (2.10-12.2)×10−6	−0.10 (−0.15-−0.04)%
Height (difference per cm of height)	3.08 (−0.98-7.14)×10−6	0.19 (0.15-0.24)%
White	Reference	Reference
Chinese vs. White	−1.88 (−2.81-−0.96)×10−4	−3.77 (−2.78-−4.75)%
African American vs. White	−3.06 (−3.70-−2.42)×10−4	−0.09 (−0.81-0.62)%
Hispanic vs. White	−2.81 (−3.55-−2.07)×10−4	1.15 (0.33-1.97)%
Overall test for race/ethnicity	p=7.6×10−23	p=1.1×10−13

Intercept: mixed model intercept coefficient corresponding to group difference between geometric means in percent; slope: mixed model slope coefficient corresponding to distensibility coefficient difference by group; 2^*slope=difference in distensibility coefficient; to allow for judging of magnitude of coefficients, the standard deviation (SD) of distensibility coefficient=1.1×10⁻³; for example, the beta coefficient for age in women is −5.04×10⁻⁵/mm Hg. This means that, on average, keeping other covariates constant, if 2 women differ 1 year in age, the older would have DC lower by −5.04×10⁻⁵/mm Hg, which corresponds to 0.045 SD units. The SI unit for distensibility, kPa⁻¹=7.5 mm Hg⁻¹.