Examination of Factors Influencing Clinical Trial Completion Among a National Sample of Middle-Aged Adults Aging with Their Long-Term Physical Disability

Adults aging into midlife (45-64) with their long-term physical disability (LTPD) face new secondary health conditions (SHCs) that increase psychosocial distress and reduce self-efficacy. Neighborhood disadvantage, measured using the Area Deprivation Index (ADI), may compound these challenges; however, little is known about how these factors influence clinical trial completion, including intervention completion, among this population. The present study examines whether: 1) self-efficacy and ADI predict clinical trial completion, and 2) self-efficacy, ADI, and average amount of clinical contact per intervention session predict intervention completion among middle-aged adults (n=507) with a LTPD enrolled in a national health behavior clinical trial. Hierarchical logistic regression showed that self-efficacy, but not ADI (in most circumstances), significantly predicted study completion. As a result, ADI was excluded from subsequent models. Logistic regression showed that self-efficacy—but not clinical contact—predicted intervention completion, though this was only found when all participants randomized to the intervention arm (EnhanceWellness-Disability; EW-D) were included. Participants who were randomized to the EW-D intervention but never initiated session 1 had lower median self-efficacy than those who initiated the intervention. Exploratory analyses (chi-square, Kruskal-Wallis, Fisher’s exact test, and between-subjects ANOVA) demonstrated that interventionist assignment related to study satisfaction and clinical contact, but not intervention completion. Giving participants the option to choose (no, yes) how intervention sessions were completed did not affect satisfaction. Results highlight the importance of emphasizing self-efficacy early in interventions to improve retention and that intervention implementation characteristics may be less critical in clinical trial outcomes than person-level factors. Future research should explore neighborhood factors in a larger sample of adults living with LTPD and identify strategies for increasing study and intervention completion among those lowest in self-efficacy.