STROKE INCIDENCE AND CASE-FATALITY IN AUSTRALASIA - A COMPARISON OF THE AUCKLAND AND PERTH POPULATION-BASED STROKE REGISTERS

Background and Purpose Population-based studies are crucial for identi fying explanations for the decline in mortality from stroke and for ge nerating strategies for public health policy. However, they present pa rticular methodological difficulties, and comparability between them i s generally poor. In this article we compare the incidence and case fa tality of stroke as assessed by two independent well-designed incidenc e studies. Methods Two registers of acute cerebrovascular events were compiled in the geographically defined metropolitan areas of Auckland, New Zealand (population 945 369), during 1991-1992 for 12 months and Perth, Australia (population 138 708), during 1989-1990 for 18 months. The protocols for each register included prospective ascertainment of cases using multiple overlapping sources and the application of stand ardized definitions and criteria for stroke and case fatality. Results In Auckland, 1803 events occurred in 1761 residents, 73% of which wer e first-ever strokes. The corresponding figures for Perth were 536 eve nts in 492 residents, 69% of which were first-ever strokes. Both studi es identified a substantial proportion of nonfatal strokes managed sol ely outside the hospital system: 28% in Auckland and 22% in Perth of a ll patients registered. The age-standardized annual incidence of strok e (all events) was 27% higher among men in Perth compared with Aucklan d (odds ratio, 1.27; P=.016); women tended to have higher rates in Auc kland, although these differences were not statistically significant. In both centers approximately a quarter of all patients died within th e first month after a stroke. There were significant differences in th e prevalence of hypertension among first-ever strokes. Conclusions The se two studies emphasize the importance of identifying all patients wi th stroke, both hospitalized and nonhospitalized, in order to measure the incidence of stroke accurately. The incidence and case fatality of stroke were remarkably similar in Auckland and Perth in the early 199 0s. However, there are differences in the sex-specific rates that corr espond to differences in the pattern of risk factors.