title: Participant characteristics and study features associated with high retention rates in a longitudinal investigation of type 1 diabetes mellitus.
abstract: BACKGROUND
  The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study has sustained an extraordinarily high level of participant involvement for over two decades.
  
  
  OBJECTIVE
  In order to identify specific characteristics of EDIC that contributed most strongly to retention, study-designed questionnaires were distributed to 1334 participants.
  
  
  METHODS
  Confidential questionnaires were completed during EDIC Years 15-17. Participants were classified as Completely Adherent (completed all visits), Partly Adherent (missed >1 visit or major portion of a visit), or Inactive (did not participate for >5 years). Questionnaire items addressed specific aspects of clinic visits, evaluation procedures, staff-participant relationships, and medical/health-care support provided by EDIC.
  
  
  RESULTS
  The most commonly cited reasons for continuing participation were Cutting Edge Tests to assess diabetes complications (79.3%), Annual Evaluations (67.7%), a desire to Help Others (65.2%), and Better Care for Diabetes (61.6%). Women chose Cutting Edge Tests as their first or second most important reason significantly more often than men, whereas men chose Better Care for Diabetes more frequently. Individuals with at least three diabetes-related complications were more likely than those with fewer complications to choose Annual Evaluations as their first or second reason for continued involvement.
  
  
  CONCLUSIONS
  The small proportion of individuals who discontinued participation restricted our ability to identify factors associated with suspended involvement. In addition, our analysis is limited to a cohort with type 1 diabetes followed in an observational study after an average participation time of 6.5 years in a randomized trial.
  
  
  CONCLUSIONS
  The primary reasons identified by respondents for their long-term commitment are consistent with shorter-term studies and underscore the importance of expert medical care, supportive staff-participant relationships, and involvement with clinically and scientifically meaningful research.
authors.affiliation: Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, 52242-1000, USA. john-kramer@uiowa.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Kramer
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Bayless
authors.forename: Gayle M
authors.initials: GM
authors.lastname: Lorenzi
authors.forename: Georgia K
authors.initials: GK
authors.lastname: Ziegler
authors.forename: Mary E
authors.initials: ME
authors.lastname: Larkin
authors.forename: Mary E
authors.initials: ME
authors.lastname: Lackaye
authors.forename: Judith
authors.initials: J
authors.lastname: Harth
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Diminick
authors.forename: Karen L
authors.initials: KL
authors.lastname: Anderson
authors.forename: Barbara H
authors.initials: BH
authors.lastname: Braffett
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Cleary
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D048909:Diabetes Complications / Q000175:diagnosis / Q000517:prevention & control; D003922:Diabetes Mellitus, Type 1 / Q000150:complications / Q000188:drug therapy / Q000628:therapy*; D004334:Drug Administration Schedule; D016903:Drug Monitoring; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010349:Patient Compliance / Q000523:psychology* / Q000706:statistics & numerical data; D011369:Professional-Patient Relations; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D007004:Hypoglycemic Agents; D007328:Insulin