Review of the long-term controlled trials of usefulness of therapy for systemic hypertension

Abstract

A number of long-term clinical trials involving over 40,000 patients have been performed to study the effectiveness of antihypertensive therapy in controlling high blood pressure and in reducing the morbidity and mortality associated with hypertension. Only diuretics and beta blockers have been studied in long-term trials to determine their efficacy in reducing cardiovascular morbidity and mortality. The Hypertension Detection and Follow-Up Program (HDFP), Medical Research Council (MRC) trial, European Working Party on Hypertension in the Elderly (EWPHE) trial, Australian Therapeutic Trial in Mild Hypertension, and the Veterans Administration Cooperative Study all showed a reduction in stroke rate. The EWPHE and HDFP trials were the only studies to show a statistically significant reduction in mortality from myocardial infarction. All of these were diuretic-based; in addition, the MRC trial also used a beta blocker as first-step therapy in 1 cohort. The International Primary Prospective Prevention Study in Hypertension and Heart Attack Primary Prevention in Hypertension (HAPPHY) trials compared beta-blocker and non-beta-blocker or diuretic-based therapies and found no significant difference between the treatment groups in the incidence of stroke or cardiac events. Neither study had a control group, so it was impossible to determine if there was any reduction in stroke or cardiac events. The Metoprolol Atherosclerosis Prevention in Hypertension trial, an extension of the HAPPHY trial, showed that smokers receiving the beta blocker metoprolol had a significantly lower cardiovascular mortality rate than those randomized to a diuretic drug. However, subgroup analysis of the HAPPHY data showed no differences in the effect of beta blockers and diuretics in smokers.(ABSTRACT TRUNCATED AT 250 WORDS)