Participant retention is one of the most critical performance metrics in clinical trials. In an era of complex protocols and decentralized models, keeping participants enrolled and engaged throughout the duration of the study is just as important as getting them in the door. High dropout rates don’t just threaten statistical power—they undermine the entire trial.

Unfortunately dropouts are all too common—average trials see 25%–30% of participants drop out, and some studies have reported attrition rates as high as 70%.¹ The consequences of poor retention are severe—from delayed timelines and escalated costs to compromised data quality and even outright trial failure.¹ In short, if recruitment fills the trial’s engine, retention is the fuel that keeps it running to the finish line.

Solving the retention challenge requires more than ad-hoc patient engagement tactics or goodwill gestures. Retention isn’t something that can be “fixed” mid-study by simply sending more reminders or motivational messages. True retention success comes from trial design—building participant-centricity into the operational and technical framework of a trial from day one.Recent research emphasizes that retention strategy plans should start during protocol development and continue through to final follow-up, because retention is a continuous process and often the Achilles’ heel of trials if not addressed early. ¹ This means rethinking how trial systems, technology, and workflows are designed to serve participants and sites in tandem.

In this article, we will unpack how thoughtful technology and operational design can significantly improve participant experience and reduce site workload, turning retention into a sustainable competitive advantage in trial delivery.

The retention imperative and its challenges

It’s no exaggeration to say that a trial’s success hinges on retention. Regulatory-quality outcomes and statistical validity depend on participants staying until endpoint assessments are completed.¹ When large proportions of patients drop out, the study loses power to detect treatment effects, wasting the efforts of those who did participate and often forcing costly extensions or protocol amendments.

A recent review noted that inadequate retention (and recruitment) is a leading cause of trial inefficiency, with an estimated 40% of studies failing to meet their target enrollment or retention numbers.¹ In some therapeutic areas, the problem is especially acute—for example, trials in Alzheimer’s disease have reported an average 30% dropout rate, and as many as 85% of those trials failed to retain enough patients to meet original statistical goals.¹ These statistics have shone a spotlight on retention for sponsors, contract research organizations (CROs), and sites alike.

Why do participants drop out? The reasons are diverse—disease burden, adverse events, lack of perceived benefit, or logistical and personal hardships can all play a role.² Surveys of trial participants consistently find that burdens and inconveniences are top drivers of dropout.² For instance, travel to the study site is often cited as the No. 1 burden contributing to discontinuation, especially when participants must travel long distances or take time off work repeatedly.² Complex visit schedules, long waits at clinics, language barriers, and cumbersome trial procedures can all erode a participant’s motivation to continue. Inadequate communication or support from the site can also leave participants feeling disconnected or unsure about the trial’s value, increasing the chance they quietly bow out. Many of these factors are modifiable if we design trials with the participant’s experience in mind.

If the fundamental design of the study remains arduous, these pain points are not always solved by well-intentioned engagement campaigns (such as newsletters, gift cards, or retention call centers). While a patient may appreciate a thank you card, it won’t outweigh the frustration of a confusing eDiary software or four separate logins to complete required tasks. As experts have argued, solving retention requires operationalizing it as a core design principle, rather than treating it as an afterthought or solely the sites’ responsibility.¹ In practice, this means including patient-centric and site-friendly elements from the very start—simplifying study tasks, integrating systems, and enabling flexibility—so that the trial is inherently easier to participate in (and manage) for its full duration.

Designing trials with the participant in mind

To improve retention, trials must be designed through the eyes of the participant. A participant-centric trial minimizes burden and maximizes convenience, understanding that an enjoyable (or at least not uncomfortable) experience is key to keeping people engaged for months or years. What does this look like in specific terms? The following are several design elements that have proven effective:

Intuitive user experience (UX) in digital platforms. From electronic diaries, patient-reported outcomes (PROs), and clinical outcomes assessments (COAs)to eConsent interfaces, the technology participants interact with should be as easy and friendly as any modern app.³ Unintuitive or clunky trial software can quickly frustrate users, especially those who are less tech-savvy or dealing with illness. By contrast, a clean, simple user interface with clear instructions and responsive design builds confidence.Participants shouldn’t need extensive training to complete a daily symptom diary or check in for a virtual visit. Thoughtful UX design—larger text options, accessible color schemes, logical navigation—can significantly reduce user error and fatigue. In turn, this boosts compliance with study tasks and makes participants more likely to stick with the trial. Good UX is a retention tool as participants are less likely to abandon a study when the digital tools feel seamless and familiar.

Multilingual and culturally adapted content. Trials increasingly span global populations, and even within one country there may be substantial language diversity.¹Providing study materials, app interfaces, and support in each participant’s preferred language is not just a regulatory box-check —it’s fundamental to retention. If participants struggle to understand visit instructions or PRO questionnaires written in an unfamiliar language, their engagement will wane. Adopting a multilingual approach (with certified translations and localized cultural nuances) helps participants feel respected and comfortable. It also improves data quality, as participants can respond more accurately when questions are in their native language.

Visit flexibility and decentralized options. One of the most powerful ways to boost retention is by meeting participants where they are—literally and figuratively.⁴ Rigid visit schedules that always require travel to a distant site at inconvenient times are a recipe for dropouts. Instead, a retention-focused trial design embraces flexibility: offering remote visit options, local labs or healthcare provider visits, and in-home services when feasible.⁴ The COVID-19 pandemic accelerated the acceptance of decentralized trial elements, and now we see their lasting benefit for retention.⁴ For example, if a participant can do a telemedicine visit for a routine check-in or have a home health nurse come to draw blood, they are less likely to withdraw due to travel burden or schedule conflicts.

Integrated reminders and participant support. Forgetfulness and feeling “out of the loop” are common contributors to non-compliance and drop-out .³ Participant-centric trials, therefore, proactively support participants with integrated reminder systems and open lines of communication. Automated reminders for medication dosing, diary entries, and upcoming visits can be delivered via the participant’s preferred channels. These reminders should be personalized and timely—for example, a text the evening before a clinic visit with what to bring, or a notification an hour before a scheduled ePRO entry.

By incorporating these elements into the trial’s operational blueprint, sponsors lay the foundation for strong retention outcomes. A 2023 review of retention strategies advised that retention efforts should start even before the first participant is recruited, and involve all stakeholders working together on a participant-first approach.¹

Mitigating ‘multiple system fatigue’ for sites

Frontline research sites are the ones who implement trial protocols and interact directly with participants, so any retention-by-design strategy must also consider the site perspective. In recent years, the proliferation of specialized eClinical tools—ePRO platform; electronic data capture; randomization and trial supply management systems, such as interactive response technology (IRT); eConsent portals; telehealth apps; etc.—has ironically created new burdens for site staff. Coordinators often find themselves juggling numerous logins and disparate systems that don’t talk to each other, leading to what we call “multiple system fatigue.”⁴

This fragmented approach increases the chance of errors and inconsistencies, and it frustrates clinical site users. Every additional system or manual reconciliation task is time taken away from patient care and engagement, which can indirectly harm retention.

The key is integration and consolidation of technology. By streamlining multiple functions into a single platform or interface, we can dramatically reduce the effort required of site personnel. Ideally, a site user has one login and one primary system through which they accomplish most trial tasks—from randomization and drug management to entering visit data and checking on patient progress.⁴ Consider the integration of eCOA tools with the IRT system. In a non-integrated setup, a participant might use a tablet or app for daily symptom diaries, while the site uses an IRT portal to manage randomization, kit assignments, and track patient status. If these are siloed, the site must separately monitor compliance in the eCOA system and manually reconcile that data with IRT records.

In an integrated approach, the participant uses one app for everything—visit notifications, diary entries, dosing reminders, and even telehealth links. On the back end, the site sees all this in one dashboard. The touchpoints are consolidated for both participant and site, cutting duplicate effort and providing richer, real-time insights.⁴

A 2023 survey of clinical research coordinators (CRCs) found that streamlining study technologies into one platform was a key recommendation for improving both site workflows and participant experiences.⁴

CRCs reported that switching between multiple systems was a major source of frustration and error. By reducing site burden through integration, sponsors free up coordinators to spend more time building participant relationships—answering questions, offering reassurance, and intervening early when engagement drops.

Retention as a dual strategy: Benefits and competitive advantage

Reframing retention as both a patient enablement and site enablement strategy changes how trials are designed and run. Participants in a well-designed trial experience a smoother, more personalized journey—they feel respected and supported, which increases their trust and willingness to remain in the study. Sites benefit from reduced workload and frustration, which helps them focus on patient care.

The benefits are measurable for sponsors and CROs: higher compliance rates, lower drop-out rates, stronger data integrity, and faster timelines.¹ Organizations that consistently deliver high-retention trials stand out as operationally excellent. Investigators prefer them, sites recommend them, and patients are more likely to enroll in future studies.

The most successful operators are those who design retention into their trials from day one. They use integrated platforms, involve patients early in usability testing, train site staff thoroughly before launch, and monitor retention metrics in real-time so they can proactively respond.

In contrast, organizations that treat retention as an afterthought often face costly fixes mid-study—scrambling to recruit replacements, extending enrollment periods, or making unplanned protocol amendments. These reactive measures rarely recover lost time and may introduce new risks.¹ Proactive retention design, on the other hand, is both more cost-effective and more sustainable, especially in an increasingly decentralized, global trial environment.

In conclusion, operationalizing participant-centric trials without increasing site burden is a key to future success. By aligning the needs of participants and sites through integrated systems, flexible designs, and supportive workflows, we can turn retention from a chronic challenge into a competitive strength—one that benefits all stakeholders, and ultimately, the patients we serve.

remain in the study. Sites benefit from reduced workload and frustration, which helps them focus on patient care.

The benefits are measurable for sponsors and CROs: higher compliance rates, lower drop-out rates, stronger data integrity, and faster timelines.¹ Organizations that consistently deliver high-retention trials stand out as operationally excellent. Investigators prefer them, sites recommend them, and patients are more likely to enroll in future studies.

The most successful operators are those who design retention into their trials from day one. They use integrated platforms, involve patients early in usability testing, train site staff thoroughly before launch, and monitor retention metrics in real-time so they can proactively respond.

In contrast, organizations that treat retention as an afterthought often face costly fixes mid-study—scrambling to recruit replacements, extending enrollment periods, or making unplanned protocol amendments. These reactive measures rarely recover lost time and may introduce new risks.¹ Proactive retention design, on the other hand, is both more cost-effective and more sustainable, especially in an increasingly decentralized, global trial environment.

In conclusion, operationalizing participant-centric trials without increasing site burden is a key to future success. By aligning the needs of participants and sites through integrated systems, flexible designs, and supportive workflows, we can turn retention from a chronic challenge into a competitive strength—one that benefits all stakeholders, and ultimately, the patients we serve.

Kees Van Ooik is Vice President of eClinical Solutions; Mike Hutton, PhD, is Director of Strategic Partnerships and Commercialization; both with Almac Clinical Technologies

References

1. Poongothai, S.; Anjana, R.M.; Aarthy, R.; et al. Strategies for Participant Retention in Long-term Clinical Trials: Participant-Centric Approaches. Perspectives in Clinical Research. 2023, 14(1), 3–9. https://pubmed.ncbi.nlm.nih.gov/36909219/

2. Anastasi, J.K.; Capila, B.; Norton, M.; McMahon, D.J.; Marder, K. Recruitment and Retention of Clinical Trial Participants: Understanding Motivations of Patients with Chronic Pain and Other Populations. Front. Pain Res. 2024. 4(3). https://doi.org/10.3389/fpain.2023.1330937

3. Frampton, G. K.; Sheperd, J.; Pickett, K.; Griffiths, G.; Wyatt, J.C. Digital Tools for the Recruitment and Retention of Participants in Randomized Controlled Trials: A Systematic Map. Trials. 2020. 21, 478. https://trialsjournal.biomedcentral.com/articles/10.1186/s13063-020-04358-3

4. Barnard, A. Easing the Clinical Trial Technology Burden on Patients and Sites. Applied Clinical Trials. April 7, 2023. https://www.appliedclinicaltrialsonline.com/view/easing-the-clinical-trial-technology-burden-on-patients-and-sites