Proband race/ethnicity affects pedigree completion rate in a genetic study of ischemic stroke

A recent meta-analysis suggested that racial/ethnic status is not a major determinant of willingness to participate in observational studies or treatment trials. However, little is known about the predictors of enrollment in family-based observational genetic studies. We tested the hypothesis that proband race/ethnicity is a significant predictor of enrolling a pedigree.

Univariable and multivariable logistic regression modeling was used to determine proband characteristics that predict DNA donation from both members of an affected sibling pair. A total of 619 adult male and female probands with first-time or recurrent ischemic stroke and a positive sibling history of stroke enrolled across 53 hospitals and clinics in the United States and Canada into the Siblings with Ischemic Stroke Study, a family-based prospective genomics study.

In univariable analysis, probands with siblings who agreed to a blood draw for DNA analyses were more likely to be male and less likely to be nonwhite. In multivariable analysis, only race/ethnicity was significantly associated with likelihood of a proband's having a sibling who agreed to a blood draw.

Contrary to observational studies that are not family based, the willingness of family members to participate in observational genetics studies may be influenced by race/ethnicity. This result reinforces the need for improving methods for recruiting diverse populations into genetic studies of stroke.