The antihypertensive and lipid lowering treatment to prevent heart attack trial (allhat): update on recruitment and baseline characteristics.

Results from past hypertension clinical trials have raised important questions concerning the type of drug used to treat high BP. It is postulated that type of drug may be important in preventing CVD independent of blood pressure lowering effects. Diuretics and some beta blockers have been previously studied in mortality and morbidity trials, but newer agents, such as calcium channel blockers, ACE inhibitors, and α blockers have not. ALLHAT is an NHLBI sponsored and industry supported clinical trial which is ongoing and designed to compare different antihypertensive drugs in preventing fatal and non-fatal CHD. The study will also test if lowering LDL-cholesterol using drugs will prevent all-cause mortality compared to no drugs. The BP study is double-blind and compares 1) amlodipine (calcium blocker); 2) lisinopril (ACE inhibitor); and 3) doxazosin (α blocker) to the diuretic chlorthalidone. The recruitment goal is 40,000 participants for the BP and lipid study who are ≥55 years old and have at least one other major CHD risk factor (one of the following): Diabetes, CVD, HDL-C<35 mg/dL, cigarette smoking, LVH on ECG, high LV mass on echo. As of December 15, 1995, 12,714 participants were randomized by 342 clinics; 41% of the participants are female; 39% are African-American; the average age of participants is 68 years; average baseline SBP is 146 mmHg, average baseline DBP is 83 mmHg. Baseline prevalence of other risk factors is: 38% have Type II diabetes; 18% have ECG LVH; 14% have low HDL-C; 18% are cigarette smokers. 41% of participants have two or more additional risk factors. Excluding Veterans Administration sites, the most productive recruitment sites have been community health centers. Factors which predict recruitment success are: fewer doctors, more nurses, and higher initial participant goals. Progress and problems encountered in ALLHAT will be discussed.