Cardiovascular morbidity and mortality in mild hypertension: the Australian Trial

The Australian Therapeutic Trial in Mild Hypertension was a controlled trial in which mildly hypertensive patients, aged between 35 and 65 years (diastolic blood pressure 95-109) were randomly assigned to take antihypertensive drugs or matched placebos for periods of up to 6 years. The overall data showed that the treated group had a lower incidence of both death and of nonfatal cardiovascular events. The differences in the incidence of noncardiovascular deaths did not differ significantly between the two groups. Univariate analysis of possible prognostic factors at the time of entry into the study showed a higher incidence of trial endpoints--mostly events due to ischemic heart disease and cerebrovascular disease--in older subjects, men, cigarette smokers and those with higher systolic blood pressures, and in thinner subjects than in others. There was a lower incidence of these events in actively treated persons than in control subjects at each level of incidence of each covariate measured. Treatment benefit was greatest in persons with lower systolic blood pressures and lower serum cholesterol levels. Multivariate regression analyses confirmed that the incidence of trial endpoints increased with age and with systolic blood pressures. There was a higher incidence in smokers than in nonsmokers, especially in those with low body weights. Treatment benefited thin smokers most, and the effects of treatment seemed to be reduced in those with higher serum cholesterol levels. There was a substantial fall in blood pressure in many of the placebo group.