Strategic Methods for Recruiting Grandparents: The Tohoku Medical Megabank Birth and Three-Generation Cohort Study

Involvement of family members, especially grandparents, in genome epidemiological research is important to investigate both genetic and environmental factors of common diseases. The aim of the present study was to establish strategies to obtain enough number of family recruitment, especially focusing on grandparents, for the Tohoku Medical Megabank Birth and Three-Generation Cohort Study. Our main strategies are summarized below. 1) We standardized informed consent process with reference materials to help people understand the consent form, 2) we created an invitation letter to contact family members, and 3) we recruited family members in several settings. To obtain informed consent, we were careful of explaining clearly the complex reasons as well as drawing people's attention. By the end of March 2017, the number of invitation letters distributed to family members through the pregnant women was 23,806, including 18,702 grandparents. Among the grandparents who received invitation letters, 2,935 (15.7%) responded to us. Furthermore, some grandparents were asked to provide informed consent with other family members by staff at maternal clinics or Community Support Centers, and others directly booked Community Support Centers without responding to the invitation letter. Grandparents joined the study anytime during mother's maternal check-ups or delivery. Overall, 8,054 grandparents participated in our birth cohort study. The setting in which most grandparents were recruited was our own facilities. Importantly, both paternal and maternal grandparents more frequently participated in the study if the father also participated. In conclusion, we are able to recruit not only pregnant women but also fathers and grandparents.