title: Impact of restricting enrollment in stroke genetics research to adults able to provide informed consent.
abstract: OBJECTIVE
  The extent of potential consent bias in observational studies elucidating genetic and environmental contributions to ischemic stroke is largely unknown. The purpose of this study was to assess differences in stroke cohort characteristics between those who provided informed consent and those whose enrollment was authorized by surrogate decision makers.
  
  
  METHODS
  The Ischemic Stroke Genetics Study (ISGS) is a prospective, 5-center, case-control study of first-ever ischemic stroke. Demographic, clinical, and stroke characteristics were compared between cases enrolled by self versus by surrogate. Data from one site that limits enrollment only to those able to self-consent were also analyzed to compare those who enrolled with those not able to consent.
  
  
  RESULTS
  Overall, 10% (54 of 517) were enrolled using surrogate authorization. Self-consented and surrogate-authorized cases did not differ significantly in age, sex, or conventional risk factors. Surrogate-authorized cases had significantly more severe stroke deficits, larger infarcts, and infarcts localizing to left supratentorial regions. Similarly, at the site restricting enrollment, stroke severity and characteristics differed between self-consented individuals and those otherwise eligible but unable to provide consent.
  
  
  CONCLUSIONS
  Failure to permit surrogate authorization in genetic studies of ischemic stroke may skew enrollment toward less severe strokes caused by smaller infarcts. This potential consent bias may undermine the ability to identify genetic determinants of risk and severity and suggests that surrogate enrollment in these studies can be ethically justifiable.
authors.affiliation: Department of Public Health Sciences, University of Virginia Center for Biomedical Ethics, University of Virginia, Charlottesville, VA, USA.
authors.forename: Donna T
authors.initials: DT
authors.lastname: Chen
authors.forename: L Douglas
authors.initials: LD
authors.lastname: Case
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Brott
authors.forename: Robert D
authors.initials: RD
authors.lastname: Brown
authors.forename: Scott L
authors.initials: SL
authors.lastname: Silliman
authors.forename: James F
authors.initials: JF
authors.lastname: Meschia
authors.forename: Bradford B
authors.initials: BB
authors.lastname: Worrall
mesh_terms: D000368:Aged; D035843:Biomedical Research; D002545:Brain Ischemia / Q000150:complications; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007258:Informed Consent; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000209:etiology / Q000503:physiopathology; D017063:Outcome Assessment, Health Care; D010560:Personnel Selection; D012720:Severity of Illness Index; D020521:Stroke / Q000150:complications / Q000209:etiology / Q000235:genetics* / Q000503:physiopathology