Mission in Sukusuku cohort, Mie: focusing on the feasibility and validity of methods for enrolling and retaining participants.

Background: We investigated the feasibility and validity of and systematized the methods used to enroll and retain participants requiring long-term interdisciplinary collaborations. We carried out this study in the Sukusuku cohort, Mie (SCM), as one of the regional research site of Japan Children's Study (JCS).

Methods: A total of 467 families who were screened between December 1, 2004 and December 31, 2005, in the Mie-chuo Medical Center and 2 other hospitals; these families were deemed eligible for the study. Of these, a total of 185 families (39.6%) participated in the 4-month observation. Of these families, 5 dropped out at month 9 of the observation; 9, at month 18; 17, at month 30; and 5, at month 42. The retention rates at 9, 18, 30, and 42 months of observation were 97.3%, 92.4%, 83.2%, and 80.5%, respectively. Reinstatement to a previous job was the most common reason for dropouts.

Results: We observed that informative consultation notes during observation were beneficial for the retention of participants, and these notes also helped in improving communication between the study subjects and the evaluators during subsequent visits.

Conclusions: In this study, we did not perform the standard checks for child development alone but also investigated the motivating influence of research partnerships with participants. Further, these visits help maintain the motivation levels of the participants and encourage them to contribute for social causes. The results present integration models that can be applied in future relevant longitudinal cohort studies in Japan.