Roughly 80% of clinical trials fail to meet their enrollment targets, and three barriers account for most of the shortfall: financial cost, travel burden, and poor outreach. Each one pushes eligible participants out of a trial before they ever get to the consent form. Sponsors and CROs that address all three, rather than picking one to fix, see the fastest gains in enrollment and retention.
Why Do Financial Costs Keep Participants Out of Clinical Trials?
Cost is often the first barrier, and it hits harder than most protocols account for. Jonathan Jackson, a researcher at Massachusetts General Hospital, has noted that many patients can't afford the costs associated with participating in a trial. Participants traveling into a research hub like Boston frequently face flights, hotels, childcare, and lost wages on top of the trial itself, and even participants who already live in the area often can't absorb the cost of repeated trips to a site.
This is a design problem, not just a budget line. If a protocol assumes participants can self-fund travel and time off work, it's already filtering out anyone who can't, which narrows the pool and skews who ends up enrolled.
How Does Travel Burden Affect Enrollment and Retention?
Geography is the single largest driver of non-participation. In one study, distance to the clinical site was the main barrier to trial participation for 60% of patients. That burden compounds with every follow-up visit a protocol requires.
Even a "nearby" site isn't automatically low-burden. A participant relying on public transit may still lose hours to schedule gaps or transfers. Someone relying on a ride from family has to coordinate pickup and drop-off around someone else's day. John Brownstein, Chief Innovation Officer at Boston Children's Hospital, has pointed this out directly: transportation is a major factor behind no-shows and dropouts, and much of what looks like a recruitment or retention problem is really a logistics problem in disguise.
Bringing certified staff and calibrated equipment to the participant, instead of asking the participant to come to a fixed site, removes this barrier without changing the assessment itself. That's the model behind 20/20 Onsite's point-of-need ophthalmic clinical trial solutions: Mobile Vision Clinics travel to the participant, and the sponsor shares or fully owns the travel burden instead of the participant.
Why Does Poor Outreach Still Undermine Patient Recruitment?
Awareness is the barrier that's easiest to overlook because it happens before recruitment even starts. If no one has heard of a trial, they can't enroll in it, no matter how well the site is set up to run it. Most participants learn about trial options from their treating physician, which means the physician must have clear, accurate eligibility information on hand.
Craig Lipset, founder of Clinical Innovation Partners and former head of clinical innovation at Pfizer, has noted that reaching patients directly can feel more "patient-centric," but failing to equip the treating doctor to have that conversation does the patient a disservice. Dr. Celette Skinner at UT Southwestern has framed the underlying issue the same way: before recruitment can improve, sponsors need to understand the full process participants go through and where it breaks down.
How Can Sponsors Reduce These Barriers Without Compromising Data Quality?
Cost, travel, and outreach gaps all point to the same fix: reduce the burden on participants without lowering the bar for execution. For trials with ocular endpoints specifically, that means calibrated equipment and certified ophthalmic technicians have to travel to the participant, not a general-purpose mobile health unit.
20/20 Onsite is built for exactly that. We're not a logistics vendor that happens to support trials. Our teams run point-of-need ophthalmic assessments under the same standardized SOPs and calibration protocols a fixed site would use, whether the visit happens at a workplace, a community location, or a participant's home. That's also how we help meet the FDA's expectations for decentralized trial execution: the data has to meet the same standard regardless of where it's collected.
If recruitment or retention is at risk on a trial with ocular endpoints, request a protocol review to see where point-of-need execution can close the gap.
Frequently Asked Questions
What are the most common barriers to patient recruitment in clinical trials? The three most common barriers are financial cost, travel burden, and poor outreach. Together, they're a major reason roughly 80% of clinical trials fail to hit their enrollment targets, and most protocols underestimate how much all three compound for a given participant.
How much does travel distance affect clinical trial enrollment? Significantly. In one study, distance to the clinical site was the main barrier to participation for 60% of patients. That burden increases with every additional in-person visit a protocol requires, which is why trials with frequent follow-up assessments see the steepest drop-off.
Why do financial costs stop eligible participants from enrolling? Participation often carries hidden costs beyond the trial itself, including travel, lodging, childcare, and lost wages from time off work. Even participants who live near a research site may not be able to absorb the cost of repeated visits, which narrows the eligible pool before recruitment even starts.
How does poor outreach limit patient recruitment? Most participants learn about trial opportunities through their treating physician rather than through direct-to-patient campaigns. If physicians don't have clear, accurate eligibility information to share, awareness stays low even when patient interest exists.
Can mobile or point-of-need models solve all three recruitment barriers? They directly address cost and travel burden by shifting logistics away from the participant. Outreach still requires a separate strategy, typically built around equipping treating physicians with clear trial information, since no execution model fixes an awareness gap on its own.
How does 20/20 Onsite reduce recruitment barriers for trials with ocular endpoints? 20/20 Onsite's Mobile Vision Clinics bring certified ophthalmic technicians and calibrated equipment directly to participants, so sponsors can shift the travel burden away from patients without lowering data quality. Our point-of-need ophthalmic clinical trial solutions follow the same standardized SOPs a fixed site would use.
Does reducing participant travel burden affect data quality? Not when the execution model is built for it. Standardized SOPs, validated equipment, and certified technicians applied consistently across all visit locations help maintain data quality, regardless of whether the assessment occurs at a site, a workplace, or a participant's home.