Ethnicity might also explain why the amlodipine combination with an ACE inhibitor or a thiazide diuretic was more efficacious than a combination of an ACE inhibitor with a thiazide diuretic in the Comparisons of Three Combinations Therapies in Lowering Blood Pressure in Black Africans trial (CREOLE), which was a randomized, single-blind, three-group trial in 621 Black patients with uncontrolled hypertension (≥ 140/90 mmHg while the patient was not being treated or was taking only one antihypertensive drug), recruited from six sub-Saharan African countries [18]. Here, ACE is linked to Hypertension.