Trends in the Incidence, Severity, and Short-Term Outcome of Stroke in Perth, Western Australia

Abstract

Background and Purpose —This report describes trends in the key indices of cerebrovascular disease over 6 years from the end of the 1980s in a geographically defined segment of the city of Perth, Western Australia. Methods —Identical methods were used to find and assess all cases of suspected stroke in a population of approximately 134 000 residents in a triangular area of the northern suburbs of Perth. Case fatality was measured as vital status at 28 days after the onset of symptoms. Data for first-ever strokes and for all strokes for equivalent periods of 12 months in 1989–1990 and 1995–1996 were compared by age-standardized rates and proportions and Poisson regression. Results —There were 355 strokes in 328 patients and 251 first-ever strokes (71%) for 1989–1990 and 290 events in 281 patients and 213 first-ever strokes (73%) for 1995–1996. In Poisson models including age and period, overall trends in the incidence of both first-ever strokes (rate ratio=0.75; 95% confidence limits, 0.63, 0.90) and all strokes (rate ratio=0.73; 95% confidence limits, 0.62, 0.85) were obviously significant, but only the changes in men were independently significant. Case fatality did not change, and the balance between hemorrhagic and occlusive strokes in 1995–1996 was almost indistinguishable from that observed in 1989–1990. Conclusions —Our results, which are the only longitudinal population-based data available for Australia for key indices of stroke, suggest that it is a change in the frequency of stroke, rather than its outcome, that is chiefly responsible nationally for the fall in mortality from cerebrovascular disease.