title: Enrollment experiences in a pediatric longitudinal observational study: The Environmental Determinants of Diabetes in the Young (TEDDY) study.
abstract: OBJECTIVE
  Our objective was to identify characteristics of infants and their families who were enrolled, refused to enroll, or were excluded from The Environmental Determinants of Diabetes in the Young (TEDDY) study.
  
  
  METHODS
  16,435 infants screened at birth and identified as at increased genetic risk for type 1 diabetes (T1DM) were placed into one of three categories: enrolled, excluded, or refused to enroll. Enrollment, exclusion and refusal rates were compared across countries and between infants from the general population (GP) and infants with a first degree T1DM relative (FDR). A multivariate logistic model was used to identify factors associated with TEDDY enrollment.
  
  
  RESULTS
  TEDDY enrollment, exclusion, and refusal rates differed by country and by GP/FDR status but reasons for refusal to enroll were similar across countries and GP/FDR populations. Sweden had the highest enrollment rate, US had the highest exclusion rate, and Finland had the highest refusal rate. FDR infants were more likely to enroll than GP infants. Inability to re-contact the family was the most common reason for exclusion. Primary reasons for refusal to enroll included protocol factors (e.g. blood draws) or family factors (e.g., too busy). Study enrollment was associated with FDR status, European country of origin, older maternal age, a singleton birth, and having another child in TEDDY.
  
  
  CONCLUSIONS
  Findings highlight the importance of country specific estimates for enrollment targets in longitudinal pediatric studies and suggest that enrollment estimates should be lowered when the study involves the general population, painful procedures, or makes multiple demands on families.
authors.affiliation: Department of Clinical Sciences, Lund University, Skåne University Hospital, CRC 72-60-11, 20502 Malmö, Sweden.
authors.forename: Barbro
authors.initials: B
authors.lastname: Lernmark
authors.forename: Suzanne Bennett
authors.initials: SB
authors.lastname: Johnson
authors.forename: Kendra
authors.initials: K
authors.lastname: Vehik
authors.forename: Laura
authors.initials: L
authors.lastname: Smith
authors.forename: Lori
authors.initials: L
authors.lastname: Ballard
authors.forename: Judy
authors.initials: J
authors.lastname: Baxter
authors.forename: Wendy
authors.initials: W
authors.lastname: McLeod
authors.forename: Roswith
authors.initials: R
authors.lastname: Roth
authors.forename: Tuula
authors.initials: T
authors.lastname: Simell
mesh_terms: D003922:Diabetes Mellitus, Type 1 / Q000209:etiology*; D004777:Environment; D005060:Europe; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D015999:Multivariate Analysis; D015997:Neonatal Screening; D019370:Observation; D018579:Patient Selection; D045808:Refusal to Participate / Q000706:statistics & numerical data*; D014481:United States