The univariate linear analysis showed that age, sex and AL were potential confounders with LP. The differences between each ethnicity's LP and RLP and those of the reference group (White) are depicted in Tables 2 and 3, respectively. Using a multivariable linear mixed-effect regression model with Whites as the comparator, adjusted for age, sex and AL, we found that significant differences exist compared to the LP in the Asian group (β coefficient = -0.14, 95% CI, -0.18 to -0.09, P<0.001), African-American group (β coefficient = -0.11, 95% CI, -0.18 to -0.04, P = 0.003) and Hispanic group (β coefficient = -0.16, 95% CI, -0.22 to -0.10, P<0.001). Thus, all other races had smaller LP than Whites. The biggest differences were seen in Hispanics and Asians compared to Whites (P<0.001).