Willingness of ischemic stroke patients to donate DNA for genetic research: a systematic review.

Systematic differences between eligible subjects who participate in research and those who do not are a form of selection bias. The aim of this study was to determine whether published reports of genetic studies of stroke provide sufficient information on the willingness of subjects to participate to assess the potential for bias. We conducted a systematic 2-person review of the English-language literature based on a MEDLINE search for studies on the genetics of ischemic stroke published between January 2000 and January 2002. Of the 41 studies that met the search criteria, only 6 (15%) provided information on the number of stroke patients who were eligible for DNA collection but refused to donate a DNA sample: 4 hospital-based case-control studies or case series and 2 population-based case-control studies of 1 cohort. The acceptance rate for participation was higher in the hospital-based case-control studies (95-99%) than in the population-based studies (75.2%). Scant data are available regarding the willingness of patients with ischemic stroke to participate in genetic studies. Methodologic and cultural differences may explain the broad range of acceptance rates for participation.