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

Abstract

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 withdrawal 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. OnTime 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 highrisk group.

Social disparities in the prevalence of diabetes in Australia and in the development of end stage renal disease due to diabetes for Aboriginal and Torres Strait Islanders in Australia and Maori and Pacific Islanders in New Zealand

“…ESRD may not be the most suitable measure of disproportionate outcomes in T1DM in Australia given that a high mortality from the disease for people of low SES before reaching ESRD is likely. Other countries have reported an inverse relationship between SES and mortality in T1DM [10–14] with a much higher likelihood of death for people who are socioeconomically disadvantaged and this disparity is more pronounced in T1DM than in T2DM [49]. For this reason, it remains uncertain whether this study demonstrates an increased risk for males or a survival advantage.…”

“…This study has also shown an increased risk of ESRD for males of low area SES. There is considerable evidence for poorer outcomes in people of low SES with T1DM [10, 14] and of the higher risk of ESRD for males [38, 39], however no other studies to date have found an increased risk of ESRD only for males of low area SES. A recent Swedish study found that being of low SES increased the risk of death two- or three-fold, and that males were more likely to die overall, but this was not explicitly examined in relation to males of low SES [40].…”

“…In contrast to T2DM no association with low area SES has previously been demonstrated for T1DM [7–9]. In Europe, Canada and the United States socioeconomically disadvantaged people have higher rates of morbidity and mortality in T1DM [10–14]. However very little is currently known regarding T1DM prevalence in Australia and the disease outcome of treated end stage renal disease (ESRD) due to T1DM for people with low area SES, this regions Indigenous minority populations, Aboriginal and Torres Strait Islanders, and Maori and Pacific Islanders.…”

Recruitment, Retention, and Blinding in Clinical Trials

“…A variety of demographic factors appear to be predictive of attrition, including older age, male gender, lower education, functional impairment, poorer cognitive performance, lower verbal intelligence, and greater comorbidities or worse physical health (Driscoll, Killian, Johnson, Silverstein, & Deeb, 2009). Transparency of the informed consent document; a strong relationship among the study coordinator, care providers, and participants; and consistency in protocols for maintaining contact with participants contribute to decreased attrition (Bedlack & Cudkowicz, 2009).…”

Adherence to study medication and visits: Data from the BABY HUG trial

“…These studies included evaluation of socioeconomic status. For example, Driscoll et al reported that pre-randomization screening of participants on both demographic and psychological variables could identify those at greatest risk for study withdrawal or poor study protocol adherence [12]. …”