Rethink clinical trial retention by shifting from isolated interventions to a holistic support system that addresses participants' needs throughout their journey.
Clinical trial retention is often approached as a series of individual interventions. A study may have participant information materials, visit reminders, reimbursement services, educational resources and study websites intended to make participation easier.
Each can be valuable. But collectively, they do not necessarily constitute a retention strategy.
Retention depends on people continuing to do what participation requires of them over weeks, months or sometimes years. They need to attend visits, prepare for procedures, take medication as required and complete assessments, while fitting the study around the rest of their lives. For caregivers, those responsibilities can extend further still.
Clinical trials have become more complex over the past decade. Studies need to answer increasingly sophisticated scientific questions and meet demanding scientific and regulatory requirements. But complexity within a protocol inevitably appears somewhere else in the system.
More visits have to be attended. More procedures need to be understood and prepared for. More assessments need to be completed. For sites, every additional requirement can create another point at which participants need explanation, reassurance or practical assistance.
This is why retention needs to be considered as more than an operational metric measured at the end of a study. Dropout is an outcome. Before somebody leaves a trial, there is usually a much longer sequence of experiences and behaviours that determines whether participation remains manageable.
Consider a participant attending a study visit involving an unfamiliar procedure for which they need to fast. The protocol requirement sounds straightforward: stop eating and drinking at a particular time and arrive at site ready for the procedure.
Doing that reliably can be considerably more complicated. The participant needs to know when to fast and understand what the procedure involves. They may be anxious about it. They need to know when to arrive and how long they are likely to be at site. They may need to arrange travel, time away from work or childcare. If a caregiver is involved, they may also be responsible for preparing the participant, explaining what will happen and managing the practicalities around the visit.
A leaflet can provide information. Travel support can help somebody get there. A reminder can prompt an action at the right moment. But the participant does not experience these as separate retention interventions. They experience a study visit they need to fit into their life.
Across our work, the needs around these moments tend to fall into four areas:
These needs rarely exist independently. Better understanding can reduce anxiety. Knowing how long a visit will take can make childcare easier to arrange. A well-timed reminder can lead somebody back to preparation information that prevents a missed or cancelled procedure.
A retention strategy therefore needs to consider how these different forms of support work together around the moments that matter.
The relationship between participants and study teams remains one of the most important forms of support within a clinical trial. Sites answer questions, explain procedures, reassure participants and learn the details about individuals that can make participation easier.
But site teams are also managing increasingly demanding protocols and growing administrative workloads. When information is difficult to find or support is poorly connected, unanswered questions often find their way back to the site.
The aim shouldn't be to replace that human relationship. It should be to make better use of it. Participants and caregivers should be able to find and revisit study-specific information when they need it. Preparation that can happen before a visit should happen before a visit. That gives site teams more time for the questions and conversations that genuinely require their expertise.
Retention therefore needs to account for the participant, the people supporting them and the realities of the site delivering the study.
Moving beyond individual interventions also changes what we measure. Distributing a leaflet is an output. Delivering a reminder is an output. Opening an application or viewing a piece of content tells us something about engagement, but relatively little about its effect.
What matters is what happens next. Did the participant arrive appropriately prepared? Did they complete the required activity? Did they contact the site before a problem became a missed visit? Did the support change a behaviour that matters to the study?
This is where behavioural data becomes valuable. Engagement can provide an intermediate signal between an intervention and outcomes such as visit preparedness, adherence, cancellations, protocol deviations and retention. It gives us a way to understand which forms of support are useful, for whom and at what point in the study. Over time, that also creates the possibility of support that responds as participants' needs change.
Rather than beginning with a list of retention interventions, I think there are three more useful questions to ask.
Information materials, travel services, reminders and other retention interventions can all be part of the answer. The opportunity is to connect them around what participants and caregivers actually need to do, and when they need support to do it.
Clinical trials will continue to become scientifically and operationally sophisticated. We should apply the same level of thought to the systems that help people take part in them.
Retention is ultimately measured by whether somebody stays in a study. If we want to influence that outcome, we need to pay much more attention to everything that happens before it.
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