In the multivariable analysis, after adjusting for the prespecified predictors such as age, sex, hypertension and time to CT, the presence of the APOE ε4 allele (OR 3.510, 95% CI 1.393–8.846, p = 0.008), but not the presence of the APOE ε2 allele (OR 0.621, 95% CI 0.203–1.901, p = 0.404), was associated with the island sign (Table 3). Here, APOE is linked to hypertensive disorder.