BACKGROUND:

The Trial of Antihypertensive Intervention Management was an extension of the NHLBI-supported Dietary Intervention Study of Hypertension (DISH) which concluded in March 1984 and showed that either weight reduction or sodium restriction diets reduced relapse rates of hypertensives who had received long-term drug treatment and then been withdrawn from drugs. TAIM was initiated in April 1984 and continued for four years at three centers and added to DISH the art of evaluating combined drug and dietary treatments. COTAIM was continued at three clinical sites in July 1988. Analysis of COTAIM results continued through November 1994 under grant R01HL40072.

DESIGN NARRATIVE:

TAIM patients were randomly assigned to one of three diets and to one of three drug regimens. The dietary interventions consisted of a weight loss program, sodium reduction with increased potassium intake, or no change in diet. The drug regimen consisted of a beta-blocker (atenolol), a thiazide-like diuretic (chlorthalidone), or placebo. The major endpoint was change in diastolic blood pressure after six months of intervention. Individuals who did not reach goal blood pressure after six months received additional drugs. Other endpoints included total risk factor score change, psychological function, and lifestyle change.

COTAIM consisted of two studies with a total of 600 subjects. COTAIM I compared the TAIM weight loss group to a randomly selected half of the usual diet group. The primary endpoint of COTAIM I was the degree of control of blood pressure on initial TAIM therapy between TAIM baseline and the end of COTAIM, a five year period.

COTAIM II added a weight loss regimen both to the sodium restriction/potassium supplementation groups and to the other half of the usual diet group. The primary outcome was control of blood pressure on initial TAIM therapy between COTAIM baseline and the end of COTAIM, a two-year period.