Incidence and Case-Fatality of Aneurysmal Subarachnoid Hemorrhage in Australia, 2008-2018

Abstract

Background: Contemporary aneurysmal subarachnoid hemorrhage (aSAH) and case-fatality studies have suggested a diminishing worldwide incidence. The purpose of this study was to examine whether such epidemiologic trends occur in Australia.

Methods: This retrospective cross-sectional study was based on data retrieved from the Nationwide Hospital Morbidity Database for all aSAH cases across hospital networks in Australia between 2008 and 2018. Information on patient characteristics, aneurysm location, procedures performed, and discharge disposition were extracted. We estimated the crude and age-adjusted incidences, trends of aSAH, and case fatality rate over time. Putative risk factors were investigated with univariate and multivariate logistic regression analysis to identify independent predictors of unfavorable discharge outcome (death and dependency).

Results: A total of 12,915 acute hospital admissions with aSAH were identified. Annual aSAH rate remained stable (mean 5.5, range 5.3-6.0 cases per 100,000 person-years) with no decline. The overall aSAH-associated 30-day case-fatality rate was 26.7% of admissions and declined by approximately 0.7% annually (P < 0.0001). Age-adjusted incidence increased with advancing age at increments of 1.3 cases per 100,000 person-years for each 5 years after the age of 40 years. Endovascular therapy accounted for 63.1% of the overall treatment strategy. Logistic regression demonstrated older age (P < 0.0001), presence of intracerebral or intraventricular hemorrhage (P < 0.0001), and hypertension (P = 0.0007) were significant predictors of unfavorable outcome.

Conclusions: A decline in 30-day case-fatality rate but not aSAH incidence from 2008 to 2018 was observed.

Keywords: Australia; Epidemiology; Incidence rate; Intracranial aneurysm; Subarachnoid hemorrhage.