Changes in Subarachnoid Hemorrhage Mortality, Incidence, and Case Fatality in New Zealand Between 1981–1983 and 1991–1993

BACKGROUND AND PURPOSE: As with total stroke, mortality rates from subarachnoid hemorrhage (SAH) have declined in New Zealand since the mid-1970s. Data from the Auckland Region Stroke studies allow an understanding of reasons for the change, as SAH incidence and 28-day case fatality rates were measured as part of population-based stroke registers. METHODS: National death registrations were used to describe the trends in mortality rates from SAH (International Classification of Diseases ICD code 430) among men and women in New Zealand. Changes in incidence and case fatality rates were determined from 2 large-scale population-based stroke registries carried out in 1981-1983 and 10 years later in Auckland. Similar methodology and case ascertainment techniques were used in both studies. RESULTS: The mortality rates from SAH declined in both men and women after the mid-1970s. The mortality rate remained higher among women than men. The incidence of SAH was lower in 1991-1993 (11.3 per 100,000) compared with 1981-1983 (14.6 per 100,000). In the younger age groups, the decrease was mostly due to a lower incidence among men, whereas in the older age groups women older than 65 years had a lower incidence. There was no consistent change in case fatality rates between the 2 periods in either men or women. CONCLUSIONS: Mortality rates from SAH have decreased in both men and women. This decrease may be explained by a decrease in the incidence of SAH, because case fatality rates showed no change.