Background: In a systematic review, published in 1997, we found that the case fatality of aneurysmal subarachnoid haemorrhage (SAH) decreased during the period 1960-95. Because diagnostic and treatment strategies have improved and new studies from previously non-studied regions have been published since 1995, we did an updated meta-analysis to assess changes in case fatality and morbidity and differences according to age, sex, and region.
Methods: A new search of PubMed with predefined inclusion criteria for case finding and diagnosis identified reports on prospective population-based studies published between January, 1995, and July, 2007. The studies included in the previous systematic review were reassessed with the new inclusion criteria. Changes in case fatality over time and the effect of age and sex were quantified with weighted linear regression. Regional differences were analysed with linear regression analysis, and the regions of interest were subsequently defined as reference regions and compared with the other regions.
Findings: 33 studies (23 of which were published in 1995 or later) were included that described 39 study periods. These studies reported on 8739 patients, of whom 7659 [88%] were reported on after 1995. 11 of the studies that were included in the previous review did not meet the current, more stringent, inclusion criteria. The mean age of patients had increased in the period 1973 to 2002 from 52 to 62 years. Case fatality varied from 8.3% to 66.7% between studies and decreased 0.8% per year (95% CI 0.2 to 1.3). The decrease was unchanged after adjustment for sex, but the decrease per year was 0.4% (-0.5 to 1.2) after adjustment for age. Case fatality was 11.8% (3.8 to 19.9) lower in Japan than it was in Europe, the USA, Australia, and New Zealand. The unadjusted decrease in case fatality excluding the data for Japan was 0.6% per year (0.0 to 1.1), a 17% decrease over the three decades. Six studies reported data on case morbidity, but these were insufficient to assess changes over time.
Interpretation: Despite an increase in the mean age of patients with SAH, case-fatality rates have decreased by 17% between 1973 and 2002 and show potentially important regional differences. This decrease coincides with the introduction of improved management strategies.
Funding: Netherlands Organisation for Scientific Research; ZonMw.