Predictors of study completion and withdrawal in a randomized clinical trial of a pediatric diabetes adherence intervention

Purpose: Loss of participants in randomized clinical trials threatens the validity of study findings. The purpose of this study was to determine pre-randomization predictors of study completion status throughout the course of a randomized clinical trial involving young children with type 1 diabetes and their primary caregivers. Methods: An intervention to improve adherence to the diabetes treatment regimen was delivered as part of the child's regular 3-month diabetes clinic visit. The study protocol involved 7 clinic visits across 18 months for the immediate Treatment group and 9 clinic visits across 24 months for the Delayed Treatment group. Among those who completed the study and regardless of treatment group, participants were categorized into two groups: On-Time Completers (n = 41) and Late Completers (n = 39). Demographic, disease, and psychosocial characteristics of children and their primary caregivers measured prior to study randomization were tested for their association with the participants' completion status (i.e., On-Time Completers, Late Completers, or Withdrawals). Results: Of the 108 participants, 28 (25.9%) withdrew and 80 (74.1%) completed the study. On-Time Completers (i.e., study completed within 4 months of expected date) were more likely to have private insurance and primary caregivers with some college education. Late Completers (i.e., study completion took longer than 4 months) were more likely to be boys and to have primary caregivers who reported mild to moderate levels of depression. Children who subsequently withdrew from the study reported poorer diabetes-related quality of life and poorer school-related quality of life at study inception and were more likely to have primary caregivers who did not work outside the home. Conclusions: Pre-randomization screening of participants on both demographic and psychological variables may help identify those at greatest risk for study withdrawal or poor study protocol adherence, permitting the investigators to develop retention strategies aimed at this high-risk group. (C) 2009 Published by Elsevier Inc.