Recruitment and Retention Strategies Recruitment and recruitment strategies occurred in two stages: (1) initial (months 0-12), the original projected enrollment period and (2) extra effort (months 13-18), the extended time necessary to achieve the enrollment goal of 1 14 subjects. Retention strategies were elaborated during the course of the study. The first child was screened in December of 2004. Enrollment was to be accomplished in 12 months. However, the last child was enrolled in June 2006 by using “extra effort” strategies to enhance enrollment.