About us

The RADIAL (Remote And Decentralized Innovative Approach to cLinical trials) trial is a pan-European phase IV proof-of-concept trial designed to evaluate the feasibility, acceptability, and quality of decentralised clinical trial (DCT) approaches compared to conventional site-based models. Conducted across six European countries, the trial involved adults with Type 2 Diabetes Mellitus (T2DM) receiving Insulin Glargine 300U/ml as part of a conventional, hybrid, or fully decentralised trial arm.

Trial objectives

The primary objectives were to evaluate possible benefits of DCTs in terms of recruitment, retention, diversity, participant and site satisfaction, and cost, in addition to determining the acceptability of a DCT approach by measuring variables related to safety, clinical oversight, treatment adherence, and data quality. Key Performance Indicators were defined and measured to assess these outcomes.

Design

Type: Phase IV, low-intervention, multi-center, open-label trial

Structure: Three-arm parallel-group trial

• Conventional arm: Site-based recruitment and visits
• Hybrid arm: Site-based recruitment with some remote elements
• Remote arm: Fully decentralized, including online recruitment and remote management

Location: Conducted in six European countries (Denmark, Germany, Italy, Poland, Spain, UK)

Participants: Adults with T2DM receiving Insulin Glargine 300U/ml

Schedule of assessment and decentralised elements

The figure below shows the schedule and type of visits and decentralised elements used in each trial arm. In total, seven decentralized elements were implemented in the RADIAL trial.

Design of the RADIAL PoC trial. DtP, Direct-to-Participant; ePRO, electronic Patient-Reported Outcome; FU, follow-up; HbA1C, glycated hemoglobin; IMP, Investigational Medicinal Product.

Key Performance Indicators (KPIs) as the main outcomes

As the RADIAL trial aimed to compare three approaches (fully decentralised, hybrid, and conventional) for scientific and operational quality, the outcomes of interest were KPIs rather than clinical endpoints The following 10 KPI were selected as main trial outcomes: Enrolment and retention rates; Participant and site staff satisfaction;  Diversity of participant population; Study cost;  Safety event reporting speed; Treatment adherence; Missing data and query rates.

Stakeholder engagement

RADIAL was co-created with patient experts and external stakeholders, including regulators and ethics committees. Engagement with the European Medicines Agency and national bodies ensured regulatory alignment and informed trial design.

Proof-of-concept design

The RADIAL trial was designed as a methodological proof-of-concept (PoC) study to evaluate whether decentralized operational approaches could be safely and effectively implemented in future trials. RADIAL provides actionable insights into how DCTs can be safely and effectively implemented in future clinical research. Conducting RADIAL as an interventional study involving an Investigational Medicinal Product (IMP) allowed the trial to undergo full regulatory review, thereby generating valuable learnings on regulatory requirements and stakeholder engagement. Importantly, RADIAL demonstrated that a PoC trial can offer more than just data—it can build capacity and foster stakeholder collaboration. The trial trained 38 sites across six countries in decentralised methods, enhancing readiness for future DCTs.