Subarachnoid hemorrhage in New Zealand: an epidemiological study.

To examine long-term trends in subarachnoid hemorrhage (SAH) mortality and morbidity, an analysis of routinely available information is presented for the 20 year period from 1959. To document the current incidence and case fatality of SAH, the results of a large scale community-based study in the Auckland region are presented. SAH mortality rates for both men and women, especially women, have declined since the mid-1970's. The decline appears to be real, and is most striking in the 45-64 year age groups. A corresponding decline in discharge rates from hospital has also occurred in these age groups. In contrast, cases fatality rates have remained stable at about 42% for the 20 year period under review. The community-based study identified 92 cases in a total population of 829,464 in a twelve month period. The age standardised incidence rates were 13.4 and 15.8 per 100,000 for men and women respectively. In the age group 25-35 years, the incidence rate was particularly high at 8.5/100,000. Case fatality at 28 days was 52%. A decline in incidence appears the most likely explanation for the overall decline in national mortality.