Recruitment and retention of participants for an international type 1 diabetes prevention trial: a coordinators' perspective.

BACKGROUND: The Trial to Reduce Insulin Dependent Diabetes Mellitus in the Genetically at Risk (TRIGR) is the first multicenter international type 1 diabetes (T1D) prevention trial to be undertaken. A unique feature of TRIGR has been recruitment of eligible pregnant women and enrollment of newborns for long-term follow-up assessments. PURPOSE: Our purpose is to summarize the recruitment and retention strategies used to conduct TRIGR from the perspective of the study coordinators. METHODS: TRIGR was designed to test whether weaning to formula containing hydrolyzed versus intact cow's milk protein would be efficacious in decreasing risk for development of T1D-associated autoantibodies and T1D among infants identified to be at increased risk for T1D based on their human leukocyte antigen (HLA) profile and family history. Multiple strategies tailored to local issues were required to enroll and follow the target number of infants. RESULTS: This study was conducted in the United States, Canada, Australia, and 12 countries in Europe. Of the 5606 mothers registered worldwide, 5000 of their infants were randomized. Of these, 2159 were HLA eligible and enrolled in the 8-month intervention and 10-year follow-up phases of this study. The TRIGR study met the accrual goal after 4.7 years of recruitment, 2.7 years longer than projected initially. Challenges included difficulty in finding fathers with T1D, a higher than expected rate of premature delivery among T1D mothers, and implementation of new privacy regulations mid-trial. The majority of participants were recruited from primary care antenatal clinics located near the study centers and from a general hospital or pediatric center that was affiliated with a TRIGR Study center. Internet and magazine advertisements were found to be useful for recruitment of families. Alternative follow-up strategies are offered to families who wish to reduce or discontinue participation. LIMITATIONS: Our experience is limited to a single international multicenter trial. CONCLUSIONS: TRIGR coordinators played key roles in the recruitment and intervention periods and continue to be instrumental in retaining families and children during the 10-year follow-up period for each child.

Use of vitamin D supplements during infancy in an international feeding trial.

OBJECTIVE: To examine the use of vitamin D supplements during infancy among the participants in an international infant feeding trial. DESIGN: Longitudinal study. SETTING: Information about vitamin D supplementation was collected through a validated FFQ at the age of 2 weeks and monthly between the ages of 1 month and 6 months. SUBJECTS: Infants (n 2159) with a biological family member affected by type 1 diabetes and with increased human leucocyte antigen-conferred susceptibility to type 1 diabetes from twelve European countries, the USA, Canada and Australia. RESULTS: Daily use of vitamin D supplements was common during the first 6 months of life in Northern and Central Europe (>80% of the infants), with somewhat lower rates observed in Southern Europe (> 60%). In Canada, vitamin D supplementation was more common among exclusively breast-fed than other infants (e.g., 71% v. 44% at 6 months of age). Less than 2% of infants in the U.S.A. and Australia received any vitamin D supplementation. Higher gestational age, older maternal age and longer maternal education were study-wide associated with greater use of vitamin D supplements. CONCLUSIONS: Most of the infants received vitamin D supplements during the first 6 months of life in the European countries, whereas in Canada only half and in the U.S.A. and Australia very few were given supplementation.