title: Time trends in outcome of subarachnoid hemorrhage: Population-based study and systematic review.
abstract: BACKGROUND
  Treatment of aneurysmal subarachnoid hemorrhage (SAH) has changed substantially over the last 25 years but there is a lack of reliable population-based data on whether case-fatality or functional outcomes have improved.
  
  
  METHODS
  We determined changes in the standardized incidence and outcome of SAH in the same population between 1981 and 1986 (Oxford Community Stroke Project) and 2002 and 2008 (Oxford Vascular Study). In a meta-analysis with other population-based studies, we used linear regression to determine time trends in outcome.
  
  
  RESULTS
  There were no reductions in incidence of SAH (RR = 0.79, 95% confidence interval [CI] 0.48-1.29, p = 0.34) and in 30-day case-fatality (RR = 0.67, 95% CI 0.39-1.13, p = 0.14) in the Oxford Vascular Study vs Oxford Community Stroke Project, but there was a decrease in overall mortality (RR = 0.47, 0.23-0.97, p = 0.04). Following adjustment for age and baseline SAH severity, patients surviving to hospital had reduced risk of death or dependency (modified Rankin score > 3) at 12 months in the Oxford Vascular Study (RR = 0.51, 0.29-0.88, p = 0.01). Among 32 studies covering 39 study periods from 1980 to 2005, 7 studied time trends within single populations. Unadjusted case-fatality fell by 0.9% per annum (0.3-1.5, p = 0.007) in a meta-analysis of data from all studies, and by 0.9% per annum (0.2-1.6%, p = 0.01) within the 7 population studies.
  
  
  CONCLUSIONS
  Mortality due to subarachnoid hemorrhage fell by about 50% in our study population over the last 2 decades, due mainly to improved outcomes in cases surviving to reach hospital. This improvement is consistent with a significant decrease in case-fatality over the last 25 years in our pooled analysis of other similar population-based studies.
authors.affiliation: University Department of Clinical Neurology, John Radcliffe Hospital, Oxford, UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Lovelock
authors.forename: G J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: P M
authors.initials: PM
authors.lastname: Rothwell
mesh_terms: D015331:Cohort Studies; D003952:Diagnostic Imaging / Q000379:methods / Q000706:statistics & numerical data; D004621:Embolization, Therapeutic / Q000379:methods / Q000706:statistics & numerical data*; D004632:Emergency Medical Services / Q000379:methods / Q000706:statistics & numerical data; D007431:Intraoperative Complications / Q000517:prevention & control; D017063:Outcome Assessment, Health Care / Q000379:methods / Q000639:trends*; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D015996:Survival Rate; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology; D014656:Vascular Surgical Procedures / Q000379:methods / Q000706:statistics & numerical data*; D020301:Vasospasm, Intracranial / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control