Stroke trends in Australia and New Zealand: mortality, morbidity, and risk factors.

Stroke death rates are declining in Australia and New Zealand as in many other industrialized countries. An explanation for the decline in mortality requires information from population-based incidence studies. Two studies that meet the criteria for well-designed stroke studies have been conducted, one in Auckland, New Zealand, in 1991 and the other in Perth, Western Australia, in 1988 to 1989. Comparisons between the two studies reveal similar incidence and case-fatality rates for both men and women, reflecting the similar mortality rates. The Auckland study repeats one carried out 10 years earlier and allows an insight into the changes in incidence, case fatality, and severity of stroke in a large urban population. Between the two study periods there was no overall change in the incidence rates but case-fatality rates improved in both men and women. Although there have been significant improvements in the level of smoking in both Australia and New Zealand during the 1980s, only marginal improvements in mean population blood pressure have occurred, despite efforts and resources directed at identification of individuals with raised blood pressure. This high-risk strategy has apparently had only a very limited impact on reducing the incidence of stroke in the population.