 The baseline characteristics of the ALLHAT participants were substantially similar in the 3 arms completing the study. Chlortalidone was significantly more effective than both amlodipine and lisinopril in achieving optimal control of blood pressure at year 1 and year 2 and more effective than lisinopril in blood pressure control at year 3, 4 and 5 all p0.001. Consistent with the better control of blood pressure, chlortalidone tended to provide a 10 more protection for combined fatal and non fatal coronary heart disease than lisinopril whereas protection was similar for amlodipine, though this protection was less evident than the superiority in controlling blood pressure. In fact, the difference in risk profile versus the lisinopril arm achieved statistical significance only for elderly and African-American participants. 