APOE and stroke disorder: demographic variables (age at baseline, sex, race, education, apolipoprotein E ε4 alleles, and study center), clinical characteristics at the index visit (BMI, smoking, alcohol, total chol., HDL, DM, use of antihypertensive drugs, and prevalent stroke); interval from the index visit to the next, mean SBP/DBP, and interactions between BPV parameters and interval