To further investigate covariate effects, we assessed age, sex, BMI, and genetic ancestry on SBP, DBP, and pulse pressure (PP) within each race/ethnicity group (Supplementary Table 1). Age and age2 accounted for substantial SBP variation as expected, ranging from 10.6% (African Americans) to 29.0% (South Asians; although this large number may simply reflect small sample size). Age explained little DBP variance in any group. BMI explained moderate SBP variance, ranging from 2.1% (African Americans) to 5.4% (South Asians). While males had higher BPs than females across groups, sex contributed little to BP variance. Although statistically significant, ancestry principal components (PCs) explained little variance for any BP phenotype in any group (generally <0.1%), except European ancestry in African Americans (1% of SBP and DBP variance, decreased SBP, DBP, and PP with lower European ancestry).
