Supplementary Material for: Patient, Family, and Center-Based Factors Associated with Attrition in Neonatal Clinical Research: A Prospective Study

<b><i>Background:</i></b> Attrition, or loss to follow-up, presents a significant threat to the integrity and validity of longitudinal clinical research. Little is known about predictors of attrition in neonatal clinical research, and no prior studies have examined how families’ experiences participating in research with their infants influences study compliance. <b><i>Objective:</i></b> To identify novel factors that were associated with attrition over 1 year of study follow-up among preterm infants enrolled in the multicenter Prematurity and Respiratory Outcomes Program (PROP) observational study. <b><i>Methods:</i></b> At discharge, research coordinators estimated the likelihood of attrition. The parents completed questionnaires about their experience with the study at discharge and at 1 year corrected age. The primary endpoint was completion of 4 PROP interviews during the first year. Logistic models were used to evaluate the associations between infant, family, and center-based characteristics and attrition. <b><i>Results:</i></b> Among 318 children, 283 (89%) met the primary endpoint. In bivariate analyses, lower maternal education, more people in the household, public insurance, and site were associated with attrition (<i>p</i> < 0.05). Parent survey responses, infant characteristics, and site characteristics were unrelated to attrition. Coordinators’ prediction of attrition was associated with completion of early study interviews; this effect waned over time. In multivariable analyses, lower maternal education and more people in the household were the factors most strongly associated with attrition. <b><i>Conclusion:</i></b> Future neonatal research should evaluate novel strategies to decrease the burden associated with study participation and reinforcement of study goals with families who have lower educational levels to facilitate participation and decrease attrition bias.