title: Risk factors for aneurysmal subarachnoid hemorrhage in a prospective population study: the HUNT study in Norway.
abstract: OBJECTIVE
  The morbidity and mortality of subarachnoid hemorrhage (SAH) are high, and established risk factors are scarce. We prospectively assessed the association of blood pressure, smoking, and body mass with the risk of aneurysmal SAH.
  
  
  METHODS
  All residents >or=20 years were invited to the Nord-Trøndelag Health (HUNT) Study (1984 to 1986) and 74,977 (88.1%) attended. The study included standardized measurements of blood pressure, body weight and height, and self-administered questionnaires. Participants who later had aneurysmal SAH (n=132) were identified, and hazard ratios (HRs), adjusted for age and sex, were estimated using Cox regression analysis.
  
  
  RESULTS
  The crude annual incidence of aneurysmal SAH was 9.9 per 100,000 people; the incidence was almost twice as high in women as in men (12.9 versus 6.8, P=0.001). Systolic blood pressure was positively associated with risk (P for trend=0.001). Compared with the reference (<130 mm Hg), the adjusted HR in people with systolic blood pressure of 130 to 139 mm Hg was 2.3 (95% CI, 1.4 to 3.8) and for systolic blood pressure >170 mm Hg, the HR was 3.3 (95% CI, 1.7 to 6.3). Diastolic pressure showed similar positive associations. Compared with never smokers, former (HR, 2.7; 95% CI, 1.4 to 5.1) and current (HR, 6.1; 95% CI, 3.6 to 10.4) smokers had substantially higher risk. Compared with normal weight (body mass index, 18.5 to 24.9 kg/m(2)), overweight people were at lower risk (HR, 0.6; 95% CI, 0.4 to 1.0).
  
  
  CONCLUSIONS
  Systolic and diastolic blood pressure were strong predictors of aneurysmal SAH, and there was a substantially increased risk associated with smoking. However, high body mass was associated with reduced risk of aneurysmal SAH.
authors.affiliation: Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Marie Søfteland
authors.initials: MS
authors.lastname: Sandvei
authors.forename: Pål Richard
authors.initials: PR
authors.lastname: Romundstad
authors.forename: Tomm Brostrup
authors.initials: TB
authors.lastname: Müller
authors.forename: Lars
authors.initials: L
authors.lastname: Vatten
authors.forename: Anne
authors.initials: A
authors.lastname: Vik
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009664:Norway / Q000453:epidemiology; D050177:Overweight / Q000150:complications / Q000453:epidemiology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D013345:Subarachnoid Hemorrhage / Q000453:epidemiology*; D011795:Surveys and Questionnaires