Contributed Commentary by Yesha Raval, Lexitas, and Chris Bartizal, Midwest Cornea Associates 

September 19, 2025 | In clinical research, keeping patients engaged throughout the course of a trial is not only a logistical goal but a scientific necessity. Retention ensures that datasets remain complete, representative, and reliable. High dropout rates, by contrast, mean gaps in data, higher costs to backfill participants, and extended timelines that frustrate everyone involved. More importantly, they undermine trust between participants, sites, and sponsors. Regulators also take notice. High dropout rates raise questions about data completeness, bias, and overall reliability, as well as make regulatory review more challenging and, in extreme cases, even prevent approval.  

Background & Site Alignment 

Retention starts with thoughtful site and study alignment. Sites that specialize in specific indications, such as dry eye or corneal disease, bring not only the right patient population but also experienced staff who know how to manage complex protocols. This familiarity streamlines scheduling, patient education, and compliance monitoring. Strong, multi-study partnerships between CROs and sites add another layer of consistency—creating shared expectations around patient communication and operational flow that improve retention across trials. 

It has been shown that alignment can make or break retention. When a cornea-focused site is asked to run a glaucoma trial, staff may be unfamiliar with the assessments, and the patient base may not match the study population. The result is slower enrollment and a higher risk of dropout. By contrast, when the right site is paired with the right study, patients are more comfortable, coordinators are confident, and patients see a positive participation experience, improving retention naturally. 

Why Retention Matters 

To understand how best to keep patients engaged, it helps first to recognize the many ways retention—or lack of it—shapes trial outcomes. 

Statistical Validity & Confidence 
When patients leave early, data are lost and bias creeps in. Those who drop out are rarely random—perhaps patients with more severe disease or those not seeing benefit. That skews results, making a therapy look better or worse than it really is. Retention also protects statistical power, or the trial’s ability to detect real treatment effects. A study planned for 300 evaluable patients can become underpowered if a quarter of patients drop out, risking inconclusive results even if the therapy works. For example, in ophthalmology, where endpoints, such as visual acuity or retinal imaging require consistent follow-up, missing data points quickly erode reliability. 

Cost & Timelines 
Replacing participants is expensive—estimated at $6,500 to $19,500 per patient—and recruitment already consumes up to 3% of trial budgets. In large trials costing tens of millions, even modest dropout adds millions in unplanned costs. Delays compound the issue. Each replacement must be screened and consented, pushing timelines back by weeks or months and costing sponsors millions in lost development time.  

Staff Morale & Participant Benefit 
Attrition is discouraging for site staff who invest time and energy into patient care. It can cause burnout and reduce enthusiasm for future trials. Participants themselves also lose out: ophthalmic patients often benefit from the closer monitoring and continuity of care trials provide. Retention protects not just science but also people. For some patients, being part of a trial means regular check-ins, access to advanced imaging, or reassurance that their condition is being closely tracked. Dropping out interrupts these benefits. 

Effective Retention Strategies 

Retention does not happen by chance—it requires a deliberate strategy that addresses both the human side of participation and the logistical realities of trial involvement. The most successful ophthalmic studies weave these elements together, ensuring that patients feel valued while also making their participation as seamless as possible. 

Engagement & Trust 
Trust is built through alignment and transparency. Sponsors, CROs, and sites must present consistent messages and prepare sites for any protocol changes that could affect operations or patient schedules. For patients, warm welcomes, familiar faces, and personal touches—like remembering a preferred appointment time—make participation feel valued. Sites that know their patient demographics often do best with retention. They understand who their patients are, what types of trials they fit best within, and any logistical hurdles, all helping match the right trial with the right type of patient. Retention strengthens when patients feel part of a “study family,” with staff recognizing compliance by explaining the impact of their contribution. Sharing progress updates, even something as simple as “you’re halfway there,” helps participants see their value in the bigger picture. 

Reducing Logistical Burden 
Support must match the burden. Fair stipends delivered promptly, gas cards, or transport services, and study meals during long visits reduce barriers to staying engaged. Technology can ease compliance too—text reminders, e-diaries, and secure portals help patients manage schedules and study requirements. Flexibility matters: offering evening visits, wide scheduling windows, or breaking up assessments shows respect for patients’ lives. Structured incentives, such as tiered stipends or mid-study bonuses, also keep motivation strong. In one year-long dry eye trial, a combination of mid-study gift cards and end-of-study bonuses helped exceed 90% retention. 

The Role of Sponsors & CROs 
Retention is not only a site responsibility. Sponsors and CROs should also carefully consider the trial’s overall burden on patients: studies with overly frequent, lengthy, or invasive procedures can discourage participants from staying the course. They must also avoid mid-study surprises—extra visits, new procedures, or added blood draws—that disrupt trust. Clear and consistent protocol design, supported by early planning and transparent communication, ensures sites can keep patients engaged without shifting expectations. Just as important is equipping sites with IRB-approved tools for outreach—whether that’s flyers, digital ads, or social media templates—to help keep participants connected and motivated. 

Conclusion 

Retention is more than a checkbox; it sets the foundation for trial success. When participants are supported through education, trust, and thoughtful logistics, they are more likely to stay. When sites are aligned with the right studies, they are better positioned to deliver consistent, complete data. And when sponsors and CROs partner closely with sites, they avoid costly disruptions that jeopardize timelines and budgets. In therapeutic areas like ophthalmology—where trials are often long and visit-heavy—retention is the linchpin. By investing in patient-centered approaches, building study-site alignment, and equipping teams with the right tools, we can safeguard validity, control costs, and deliver new treatments to patients who need them most. 

Yesha Raval is Director of Operational Strategy at Lexitas, an ophthalmology-focused CRO. She can be reached at yesha.raval@lexitas.com. 

Chris Bartizal is Clinical Research Coordinator at Midwest Cornea Associates. He can be reached at mcaresearch@midwesteye.com.