Activities & Operations

Remote recruitment and (pre-)screening

DCTs minimise or eliminate the need for travel to research sites, enabling broader accessibility for participants who are not in convenient proximity to a trial site. This enables broader outreach to potential participants through online recruitment methods such as social media ads, search engine advertisement and recruitment websites, replacing, or adding to, traditional recruitment methods. However, these methods also have their challenges, such as lower or different investigator-participant interaction and challenges in reaching and identifying eligible participants. Therefore, optimising recruitment for DCTs is essential.

Recommendations

A mixed recruitment strategy would likely be most effective, combining online methods such as social media and search advertising to generate broad awareness, and database outreach and healthcare provider referrals to target specific populations.

Although theoretically a single decentralised site could recruit participants from any place in an entire country, if that site for any reason encounters challenges in the recruitment, this can be very hard to mitigate. Selecting multiple sites mitigates risks of under-recruitment and under-performance.

Our data suggest that paid search drove more pre-screener completions, while performance max campaigns had a high volume but low engagement. Additionally, targeted keyword strategies in search advertising, aligned with condition-specific search behaviour, are essential to improve the relevance and efficiency of recruitment efforts. Future research should aim to understand the search behaviour of potential participants and further explore paid search to attract users actively searching for trial-related information.

The RADIAL trial found that 69% of candidates abandoned pre-screening at the initial data-processing consent step. To address this, future studies should design pre-screening processes that balance robust eligibility checks with clear, accessible, and participant-friendly privacy explanations. Sponsors should test and refine consent language to make it simpler and less intimidating, reducing anxiety about data use. User-testing consent steps can ensure they are understandable and minimise early attrition, supporting smoother progression through pre-screening.

This includes covering travel to drop-off points or other necessary locations, even though they do not travel to the site. Plan for patient reimbursement in future trials to enhance participation and retention.

How Trials@Home reached these recommendations

We conducted a qualitative analysis of stakeholder views about participant recruitment, retention and adherence in DCTs. Additionally, we accumulated ample operational experience in recruitment through RADIAL. While previous studies have shown that using online recruitment methods can increase recruitment rates and cost effectiveness, RADIAL experiences with online recruitment were not as successful as was anticipated. That said, recruitment is context-dependent and therefore findings cannot be fully disentangled from the context of RADIAL.

Further reading

Publications

A secondary qualitative analysis of stakeholder views about participant recruitment, retention, and adherence in decentralised clinical trials (DCTs)

Coyle, et al
Trials
2022
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Recruiting and Consenting Decentralized Clinical Trial Participants – Learnings from the Trials@Home RADIAL Proof-of-Concept Trial.

Lagerwaard, et al
Clinical Pharmacology & Therapeutics
2025
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