Blood pressure levels and mortality from cerebrovascular disease in Australia and the United States.

Blood pressure distributions were compared in two groups of subjects aged 25-64 years surveyed in the Risk Factor Prevalence Study in Australia and the Lipid Research Clinics Prevalence Study in North America. In men and women of all age groups, systolic and diastolic blood pressures were greater in the Australian study than in the North American study; the prevalence of hypertension was almost twice as great in the Australian study. The proportion of the total population receiving antihypertensive treatment was also greater in the Australian study. However, among those subjects classified as hypertensive, a greater proportion were receiving treatment in the North American study. The differences in blood pressure levels did not appear to be due to differences in body mass index. In men, possible differences in alcohol consumption could account for some of the difference in blood pressure levels but data from the Australian study suggest that such differences could only account for a small proportion of the difference in prevalence of hypertension. The higher blood pressures and greater prevalence of hypertension in the Australian study were consistent with a 40-55% greater mortality from cerebrovascular disease in Australia than the United States (1968-1977), observed in both men and women from age 45 years onwards. In Australia in 1978, this difference accounted for over 4,200 excess deaths (4% of annual mortality), 600 of which occurred in men and women below the age of 65 years. Mortality from other hypertensive diseases was also greater in Australia than in the United States, which gives further support to the suggestion that population blood pressures and hypertension-related mortality are greater in Australia than they are in the United States.