You’ve spent months recruiting patients for your Phase III trial across six countries. Sites are running. Enrollment targets are met. Then reality hits that six months in, 30% of your participants have vanished.
This is a reality for most clinical trials. The average clinical trial loses 30% of participants, and a staggering 85% of trials fail to retain enough patients to meet enrollment targets.
Most global trials face even bigger challenges. Between language barriers, failing to meet cultural expectations, and different levels of health literacy, the trust dynamics shift significantly.
Patient retention in clinical trials isn’t about keeping spreadsheet numbers up. It’s about data integrity that regulators will accept, meeting endpoints that prove your treatment works, and getting therapies to patients before your funding runs out.
Here’s why patient retention in clinical trials drops and what you can do about it.
Why Participants Drop Out of Clinical Trials
High patient burden
Clinical trials ask a lot of participants.
- Multiple site visits
- Lengthy procedures
- Detailed questionnaires
- Time away from work and family
A 2021 CISCRP survey found that 44% of participants found traveling to study sites “somewhat” or “very burdensome”. The 2019 pandemic has changed expectations, and patients who experienced virtual care now question why they need to show up in person in the first place.
Lack of clarity in trial instructions or expectations
When participants find informed consent forms difficult to understand, they’re significantly more likely to drop out. In a 2022 study, From the Patient Perspective, 58% of patients found the language in questionnaires confusing. If people don’t fully grasp what they’re signing up for, they won’t stick around when things get complicated.
Cultural or trust-related barriers
In global trials, translation plays a significant role. In Malaysia, a depression study questionnaire asked geriatric patients: “Do you prefer to stay at home, rather than going out and doing new things?” The question had zero discriminatory value for Malay patients because their culture emphasizes family living over individual lifestyle. Everyone was bound to answer yes, regardless of depression status. This renders the data point quite useless.
Cultural differences show up in unexpected ways. In Russia and Japan, cultural norms discourage questioning medical authority. In some Latin American cultures, major medical decisions involve the entire family, not just the patient.
If you don’t take these things into consideration, you’ll misinterpret dropout patterns and data quality issues.
Communication challenges due to language differences
Medical terminology often has no direct equivalent across languages. A symptom description that works perfectly in one country might mean something completely different in two countries over. Technical terms sometimes just don’t exist in certain languages, forcing translators to improvise with alternatives that may or may not capture the actual meaning.
When participants can’t accurately report symptoms or when instructions get garbled along the way, you get confusion. Confusion breeds frustration. And frustrated participants disappear.
Side effects or perceived lack of benefit
This is often unavoidable, but clear communication can help manage expectations. When patients understand potential side effects upfront and have proper support channels, they’re more likely to report issues rather than simply disappearing.
5 Tips for Improving Patient Retention in Clinical Trials
Here are five patient retention strategies that keep participants engaged throughout your study:
1. Simplify and Localize Patient-Facing Materials
Translation is not localization. Translating your consent form from English to Spanish is step one. Localizing it for Mexican patients, Argentine patients, and Spanish patients is step two.
Professional clinical trial translation services go beyond word-for-word conversion. They adapt content for literacy levels, cultural contexts, and regional medical terminology.
Don’t forget about multilingual digital tools. Patient portals, electronic consent forms, and mobile apps need proper localization for user interface elements, date formats, measurement units, and cultural expectations around privacy and data sharing.
2. Train Site Staff to Communicate Consistently
Your protocol is only as good as the people implementing it. In global trials, site staff are your front line, and they need training that goes beyond the protocol itself.
Staff must understand how to communicate clearly with participants who speak different languages or come from different cultural backgrounds. Site staff should also receive training on cultural factors that affect participation. For example, in some countries, such as Jordan, India and parts of Africa, women need family permission to participate in trials.
3. Provide Clear, Ongoing Support
Recruitment is about getting patients in the door. Retention is about supporting them every day after that.
90% of study volunteers want to receive updates about trial progress. Yet many trials go radio silent after enrollment, leaving participants wondering if their time matters or if the study is even still happening.
Create multiple channels for participants to ask questions or report concerns:
- Phone support in their native language
- Text messaging for quick check-ins
- Patient portals for reviewing their own data
Different participants prefer different communication styles, and offering options increases the likelihood they’ll actually reach out when problems arise, rather than just dropping out.
4. Reduce Participant Burden Where Possible
Every site visit, every procedure, every questionnaire adds to participant burden. You can’t eliminate all of it; that’s the nature of research, but you can be strategic about minimizing unnecessary demands.
Offer flexible scheduling when possible:
- Evening and weekend appointments accommodate working participants.
- Home visits or mobile units reach people with transportation challenges or mobility limitations.
- Decentralized clinical trial models that bring services to participants rather than forcing participants to travel to sites
Provide appropriate compensation, not just for participation, but for time, travel, and related expenses.
5. Gather and Act on Patient Feedback
The best retention strategies come from asking participants what they actually need. Unfortunately, many trials wait until someone drops out to ask what went wrong.
Implement regular feedback mechanisms throughout your trial.
- Brief check-ins during site visits
- Anonymous surveys at key milestones
- Exit interviews with participants who withdraw
This feedback reveals patterns you might not otherwise see.
More importantly, act on what you learn. When participants see that their feedback leads to actual changes, it reinforces that their experience matters and builds the trust that keeps them engaged.
Ready to Stop Losing Patients Halfway Through Your Trials?
At EC Innovations, we help clinical trial sponsors, CROs, and research sites solve the communication problems that drive dropout rates through the roof.
Our clinical trial translation services go beyond word-for-word translation to deliver patient-facing materials that participants actually understand.
We’ve seen it happen too many times: a trial loses participants because nobody caught what it was that was causing the drop in patient retention in clinical trials in the first place.
Our team works with you to develop communication strategies that keep participants engaged from enrollment through study completion. Site staff training resources in multiple languages. Multilingual support tools that make it easy for participants to ask questions and report concerns.
The difference between a trial that finishes on schedule and one that bleeds participants for two years often comes down to whether participants genuinely understand what they signed up for, feel supported throughout the process, and trust that their participation matters.
We also provide specialized support for eCTD submissions and other regulatory documentation needs across global markets. Contact us to discuss how we can help you improve retention outcomes in your next international clinical study.
