title: Risk of subarachnoid haemorrhage in first degree relatives of patients with subarachnoid haemorrhage: follow up study based on national registries in Denmark.
abstract: OBJECTIVE
  To estimate the risk of occurrence of subarachnoid haemorrhage in first degree relatives (parents, siblings, children) of patients with subarachnoid haemorrhage.
  
  
  METHODS
  Population based cohort study using data from the Danish National Discharge Registry and the Central Person Registry.
  
  
  METHODS
  Incident cases of subarachnoid haemorrhage admitted to hospital from 1977 to 1995 (9367 patients) and their first degree relatives (14 781).
  
  
  METHODS
  The incidence rate of subarachnoid haemorrhage was determined for the relatives and compared with that of the entire population, standardised for age, sex, and calendar period. This process was repeated for patients discharged from neurosurgery units, as diagnoses from these wards had high validity (93%).
  
  
  RESULTS
  18 patients had a total of 19 first degree relatives with subarachnoid haemorrhage during the study period, corresponding to a standardised incidence ratio of 2.9 (95% confidence interval 1.9 to 4.6). Patients discharged from neurosurgery wards had a higher standardised incidence ratio (4.5, 2.7 to 7.3).
  
  
  CONCLUSIONS
  First degree relatives of patients with subarachnoid haemorrhage have a threefold to fivefold increased risk of subarachnoid haemorrhage compared with the general population.
authors.affiliation: Epidemiology, Institute of Public Health, Universtity of Southern Denmark, Odense University, DK 5000 Odense C, Denmark. d-gaist@win-chs.ou.dk
authors.forename: D
authors.initials: D
authors.lastname: Gaist
authors.forename: M
authors.initials: M
authors.lastname: Vaeth
authors.forename: I
authors.initials: I
authors.lastname: Tsiropoulos
authors.forename: K
authors.initials: K
authors.lastname: Christensen
authors.forename: E
authors.initials: E
authors.lastname: Corder
authors.forename: J
authors.initials: J
authors.lastname: Olsen
authors.forename: H T
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D012042:Registries; D012307:Risk Factors; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology / Q000235:genetics*