"Size is not everything": the Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT)

ALLHAT, the largest ever antihypertensiv e trial, compared cardiac outcomes in 42,418 high-risk individuals with mild-to-moderate hypertension, including 36% with diabetes, randomised to: 1) the thiazide-type diuretic, chlorthalidone; or 2) the ACE inhibitor, lisinopril; or 3) the calcium channel blocker, amlodipine. No differences between the groups were observed for the primary outcome coronary heart disease (CHD) but chlorthalidone was superior in preventing some cardiovascular disease events. Since diuretics are less expensive, it might be inferred that these drugs should be the preferred first-line antihypertensive therapy. However, the design and conduct of ALLHAT make interpretation of the results difficult. Despite its size, ALLHAT has few practical implications for management of hypertension.