Factors impacting enrollment in a multi-site international feeding trial

Background: Diverse communities, cultures and resources may influence recruitment and enrollment of participants for community based trials. An examination of enrollment into a community-based, complementary feeding study in four countries may help to better understand these factors.

Study design: An efficacy study of two complementary feeding regimens in 1200 6–18 month old infants was conducted in the Democratic Republic of Congo (DRC), Guatemala, Pakistan and Zambia. Infants 3-4 months of age, that were primarily breastfed and whose mothers intended to continue breastfeeding to 12 months were eligible for participation. Formula feeding, known birth defect or neurological disorder, and being a sibling of a multiple birth were exclusion criteria. Eligibility, enrollment and refusal rates were summarized across sites. Results: A total of 2412 mothers were interviewed to screen infants for eligibility. 1732 (72%) infants were determined eligible. Rates of eligibility varied from 57% to 95%. Formula feeding was the primary reason for ineligibility (80%). Of those eligible, 1233 (71%) enrolled into the study. Participation was refused for 499 infants. The primary reasons included spousal disapproval (47%), lack of time (35%); lack of interest (20%), fear of blood draw (18%), disagreement with home visits (17%) and disapproval by other family member (7%).

Conclusions: Rates of eligibility in Zambia and DRC were high and those eligible almost uniformly agreed to enroll. Pakistan and Guatemala had lower eligibility and higher refusal rates. Spousal influence and study demands strongly affected refusal rates. These and other cross-cultural factors should be considered when planning similar interventions.