Therapeutic implications from clinical trials for the treatment of hypertension

A total of eight therapeutic trials have now been completed, which were designed to see if antihypertensive drug therapy would reduce cardiovascular mortality in patients with mild degrees of hypertension. The design of most of the trials was similar: Patients with uncomplicated primary hypertension, with diastolic blood pressure (DBP) >90 or 95 mmHg after a few sets of measurements, were randomly assigned to either placebo tablets or active drug. In all but one, the MRC trial, the active drug given first (and often exclusively) was a diuretic. In the MRC trial, as described in Miall's paper, half of the treated patients received a beta blocker. In the European trial in the elderly, a potassium-sparing agent, triamterene, was given with the diuretic. In the subsequent analyses of these trials, the first two, the VA trial reported in 1970 and the U.S. PHS trial reported in 1977, will be excluded because the number of patients enrolled were too few to provide statistically significant data. Their results did, however, show apparent protection against overall cardiovascular morbidity, but like most of the others to be analyzed, no significant reduction in coronary morbidity or mortality. Although the primary aim of these trials was to see whether therapy reduced cardiovascular complications, they provide insights into the answers to two major questions: 1) Which patients should be treated with drugs, and 2) which form of therapy is best. In other words, who should be treated and how should treatment be given?