Participant satisfaction across three trial arms with varying degrees of decentralisation in the RADIAL...

As clinical trials increasingly adopt decentralised elements to potentially reduce burden and enhance participant inclusion, data on participant experience and satisfaction becomes essential to inform future decentralised trial designs. This study investigated participant satisfaction in three trial arms: a fully decentralised arm, a hybrid arm and a conventional arm in individuals with type 2 diabetes mellitus.

RADIAL, a three-arm, low-intervention, phase IV proof-of-concept trial, was set up in six European countries and aimed to evaluate the scientific and operational quality as well as the feasibility of trial approaches with different levels of decentralisation. Participant satisfaction was measured at three time points: at start (week 0), during (week 12), and at the end of the trial (week 24), using digital questionnaires.

In all arms, 72% to 100% of participants were satisfied with overall trial participation, but satisfaction decreased over time in the hybrid arm compared to the conventional arm. Participants reported issues with trial technologies as reasons for their dissatisfaction in the hybrid arm, which was further substantiated by dissatisfaction with specific digital trial components. Satisfaction with the time commitments and data collection was also lower in the hybrid arm than in the conventional arm. Nevertheless, participants in both arms were very satisfied with the comprehensibility of the information before trial start, feeling of safety, interaction with trial staff, and timing of trial appointments, ranging from 92% to 100%. Due to the small number of seven participants in the remote arm, no meaningful conclusions on satisfaction could be drawn in this arm.

Decentralisation seems to be acceptable to trial participants, as trial activities can be responsibly shifted from the research site to participants' homes, e.g. decentralised, without materially impacting participant satisfaction. However, technological issues negatively affected satisfaction in the hybrid arm, highlighting the need to utilise fit-for-purpose technologies and adequately address potential digital challenges in trials. Including participant satisfaction measures in trials deepens the understanding of how participants experience different (decentralised) trial activities, which can help to tailor future trials to their needs.

ClinicalTrials.gov NCT05780151 (2023-03-08) and CTIS 2022-500,449-26-00 (2022-03-28).