Medical Research Council trial of treatment of hypertension in older adults: principal results. MRC Working Party.

OBJECTIVE: To establish whether treatment with diuretic or beta blocker in hypertensive older adults reduces risk of stroke, coronary heart disease, and death. DESIGN: Randomised, placebo controlled, single blind trial. SETTING: 226 general practices in the MRC general practice research framework. SUBJECTS: 4396 patients aged 65-74 randomised to receive diuretic, beta blocker, or placebo. Patients had mean systolic pressures of 160-209 mm Hg and mean diastolic pressures less than 115 mm Hg during an eight week run in and were not taking antihypertensive treatment. INTERVENTION: Patients were randomised to atenolol 50 mg daily; hydrochlorothiazide 25 mg or 50 mg plus amiloride 2.5 mg or 5 mg daily; or placebo. The regimens were adjusted to achieve specified target pressures. Mean follow up was 5.8 years. MAIN OUTCOME MEASURES: Strokes, coronary events, and deaths from all causes. RESULTS: Both treatments reduced blood pressure below the level in the placebo group. Compared with the placebo group, actively treated subjects (diuretic and beta blocker groups combined) had a 25% (95% confidence interval 3% to 42%) reduction in stroke (p = 0.04), 19% (-2% to 36%) reduction in coronary events (p = 0.08), and 17% (2% to 29%) reduction in all cardiovascular events (p = 0.03). After adjusting for baseline characteristics the diuretic group had significantly reduced risks of stroke (31% (3% to 51%) p = 0.04), coronary events (44% (21% to 60%), p = 0.0009), and all cardiovascular events (35% (17% to 49%), p = 0.0005) compared with the placebo group. The beta blocker group showed no significant reductions in these end points. The reduction in strokes was mainly in non-smokers taking the diuretic. CONCLUSION: Hydrochlorothiazide and amiloride reduce the risk of stroke, coronary events, and all cardiovascular events in older hypertensive adults.