title: Longitudinal risk of intracranial hemorrhage in patients with arteriovenous malformation of the brain within a defined population.
abstract: OBJECTIVE
  Accurate estimates for risk and rates of intracranial hemorrhage (ICH) in the natural course of patients harboring brain arteriovenous malformation (BAVM) are needed to provide a quantitative basis for planning clinical trials to evaluate interventional strategies and to help guide practice management.
  
  
  METHODS
  We identified patients with BAVM at the Kaiser Permanente Northern California health maintenance organization and documented their clinical course. The influences of age at diagnosis, gender, race-ethnicity, ICH at presentation, venous draining pattern, and BAVM size on ICH subsequent to presentation were studied using the multivariate Cox proportional hazards model and Kaplan-Meier curves.
  
  
  RESULTS
  We identified 790 patients with BAVM (51% female; 63% white; mean age+/-SD at diagnosis: 38+/-19 years) between 1961 and 2001. Patients who presented with ICH experienced a higher rate of subsequent ICH than those who presented without ICH under multivariate analysis (hazard ratio, 3.6; 95% CI, 1.1 to 11.9; P<0.032). The effect was similar across race-ethnicity and gender. This difference in ICH rates was greatest in the first year (7% versus 3% per year) and converged over time. The effect of subsequent ICH on functional status was similar to that of the initial ICH.
  
  
  CONCLUSIONS
  Presentation with ICH was the most important predictor of future ICH, confirming previous studies. Future ICH had similar impact on functional outcome as incident ICH. Intervention to prevent ICH would be of potentially greater benefit to patients presenting with ICH, although the advantage decreases over time.
authors.affiliation: Department of Anesthesia, University of California San Francisco, San Francisco, Calif 94110, USA.
authors.forename: Alexander X
authors.initials: AX
authors.lastname: Halim
authors.forename: S Claiborne
authors.initials: SC
authors.lastname: Johnston
authors.forename: Vineeta
authors.initials: V
authors.lastname: Singh
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.forename: John P
authors.initials: JP
authors.lastname: Bennett
authors.forename: Achal S
authors.initials: AS
authors.lastname: Achrol
authors.forename: Stephen
authors.initials: S
authors.lastname: Sidney
authors.forename: William L
authors.initials: WL
authors.lastname: Young
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications*; D020300:Intracranial Hemorrhages / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors