• ALLHAT
• diuretics
• hypertension

• ACE, angiotensin converting enzyme
• ALLHAT, antihypertensive and lipid lowering treatment to prevent heart attack trial
• CCB, calcium channel blocker

The presentation and publication of the primary results of the antihypertensive and lipid lowering treatment to prevent heart attack trial (ALLHAT) has generated much interest and opinion.¹ This is because (1) ALLHAT is the largest ever study of antihypertensive therapy; (2) ALLHAT addressed the commercially sensitive issue of appropriate first line therapy for hypertension; and (3) the initial presentation of the results led to some controversial conclusions.

ALLHAT was designed to compare the effectiveness of initial antihypertensive therapy with three different classes of “newer” antihypertensive drug classes (angiotensin converting enzyme (ACE) inhibitor, calcium channel blocker (CCB) or α adrenergic blocker) with an older established treatment (thiazide diuretic) at reducing a primary end point of fatal coronary heart disease or non-fatal myocardial infarction. ALLHAT was a randomised, double blind controlled clinical trial conducted in 623 centres across North America. ALLHAT initially randomised 42 418 mild to moderate hypertensive patients aged ≥ 55 years (mean age 67 years) with one additional cardiovascular risk factor to one of four antihypertensive treatments; the diuretic, chlorthalidone (12.5–25 mg daily); the ACE inhibitor, lisinopril (10–40 mg daily), the CCB, amlodipine (2.5–10 mg daily), or the α blocker doxazosin (1–8 mg daily). The doxazosin arm …