BACKGROUND:

Dietary sodium reduction has a mild effect on the reduction of hypertension. Weight loss, while achievable in the short-run with diet alone, may also have only mild effects on hypertension and is very difficult to maintain with diet and/or behavior modification. Alteration of patients' lifestyles to decrease excessive alcohol intake is somewhat controversial. Medications, on the other hand, have clear benefits in terms of blood pressure lowering, and in the case of diuretics and beta-blockers, reduction in cardiovascular morbidity and mortality. However, there is concern about their justified use in mild hypertension since each one has side effects, some of which may have long-term implications, such as alteration in serum lipids. Newer classes of drugs--calcium antagonists, angiotensin converting enzyme inhibitors, alpha blockers--had not previously been compared long-term with diuretics and beta-blockers.

DESIGN NARRATIVE:

TOMHS I enrolled 902 men and women to determine the feasibility of a larger trial. Participants were randomized in a double-blind manner to one of six treatment groups and within two strata. Stratum I was for participants not on antihypertensive drugs and Stratum II for those on antihypertensive drugs at initial screening. There were six treatment arms: placebo, a diuretic (chlorthalidone), a beta-adrenergic blocking agent (acebutolol), an alpha blocker (doxazosin mesylate), a calcium antagonist (amlodipine maleate), and an angiotensin converting enzyme inhibitor (enalapril maleate). All participants received a lifestyle intervention program that included reduction of sodium chloride and alcohol intake as well as weight reduction and increase in physical activity. All participants were followed for at least 48 months, with an average of 54 months. The primary endpoint was lowering of blood pressure. The treatments were also compared for effects on blood chemistries including lipoproteins, echocardiographic left ventricular mass, ventricular ectopic activity and ST-T changes of ischemia as measured by ambulatory ECG monitoring, side effects, and quality of life. Randomization took place between October 1986 and March 1988. Active follow-up ended in March-April 1992. Data analysis ended in May 1994.