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(Stroke. 2008;39:831.)
© 2008 American Heart Association, Inc.

Original Contributions

Impact of Restricting Enrollment in Stroke Genetics Research to Adults Able to Provide Informed Consent

Donna T. Chen, MD, MPH; L. Douglas Case, PhD; Thomas G. Brott, MD; Robert D. Brown, Jr, MD; Scott L. Silliman, MD; James F. Meschia, MD; Bradford B. Worrall, MD, MSc for the ISGS Investigators^*

From the Department of Public Health Sciences (D.T.C., B.B.W.), the Department of Psychiatric Medicine (D.T.C.), the Department of Neurology (B.B.W.), and the University of Virginia Center for Biomedical Ethics (D.T.C.), University of Virginia, Charlottesville, Va; the Department of Public Health Sciences (L.D.C.), Wake Forest University, Winston-Salem, NC; the Department of Neurology (T.G.B., J.F.M.), Mayo Clinic, Jacksonville, Fla; the Department of Neurology (R.D.B.), Mayo Clinic, Rochester, Minn; and the Department of Neurology (S.L.S.), University of Florida, Jacksonville, Fla.

Correspondence to James F. Meschia, Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224. E-mail meschia.james{at}mayo.edu

Background and Purpose— 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.

Key Words: consent bias • ischemia • research ethics • stroke

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