Patient dropout is one of the most expensive and least predictable risks in trial execution. When participants exit early, sponsors and CROs not only lose headcount; they also lose data continuity, add timeline pressure, increase monitoring and operational churn, and often introduce avoidable risk of protocol deviation.
This article breaks down why patient dropout happens, what proven clinical trial retention approaches look like in practice, and how to design retention into the protocol so you are not scrambling after attrition starts showing up in your weekly reports.
Patient dropout rates in clinical trials vary by therapeutic area, study design, and participant population. Industry analyses have estimated overall dropout rates of around 30% in some datasets, and other sources cite ranges of roughly 15% to 40%, depending on the trial context. (ACRP)
Dropout is also trending in the wrong direction in at least some broad industry analyses. One Applied Clinical Trials analysis reported an increase in average dropout across studies and therapeutic areas from 15.3% to 19.1% over a seven-year period, a 25% increase. (Applied Clinical Trials Online)
These numbers matter because retention is not just a “people problem,” it is a feasibility problem. Higher dropout can mean:
It is also expensive. One commonly cited estimate pegs average recruitment cost at around $6,533 per participant, and replacement costs are higher, around $19,533 in some scenarios. These figures vary by study, but they illustrate why preventing avoidable dropout is often cheaper than “recruiting your way out of attrition.” (mdgroup)
Most dropout drivers are predictable. The mistake is treating retention as a downstream “site performance” issue instead of a design and execution issue.
Travel time, visit frequency, time away from work or caregiving, transportation reliability, and out-of-pocket costs all stack up. The more complex the visit schedule, the more fragile retention becomes, especially for participants who already face access barriers.
Every added step is a dropout opportunity. Long, repetitive, or confusing processes contribute to early disengagement and increase the likelihood of missed visits or non-compliance.
Two common friction points:
Participants rarely drop because they “stopped caring.” They drop because they feel uncertain, unsupported, or disconnected.
Common triggers:
Even when compensation exists, reimbursement can be slow, inconsistent, or incomplete. Parking, meals, childcare, rideshare costs, and missed wages can be enough to push a participant out of the study.
A practical way to think about clinical trial retention is this: reduce burden, increase flexibility, and remove friction before the first participant is enrolled. Systematic reviews of retention strategies commonly highlight categories such as flexibility, incentives, reminders, and persistent follow-up as effective in practice. (PMC)
Here are retention strategies that consistently map to the realities of sponsor and CRO execution.
Retention should be treated like recruitment, with a plan, owners, and measurement. Before DBL, you want answers to:
Deliverable to create: a one-page retention plan that includes burden drivers, mitigation tactics, communication cadence, and rescue triggers.
Not every trial can be decentralized, and not every assessment can be moved off-site. But well-designed hybrid approaches can reduce participant effort without sacrificing data quality.
Options to consider, depending on protocol and endpoints:
The retention “win” here is simple: fewer travel legs and fewer hours lost, which reduces missed visits and dropout risk.
Retention improves when participants feel supported and confident.
Operational best practices:
You cannot remove endpoint-critical assessments, but you can:
If reimbursement is slow or unclear, you are creating dropout pressure.
Fixes that work:
You do not need a “best practice target” table to run retention well. You need consistent signals, trend visibility, and clear triggers.
Metrics many teams track for clinical trial retention:
When a trigger fires, the question is not “why are they non-compliant,” it is “what friction can we remove this week to keep data continuity intact?”
If your trial includes ocular endpoints, retention risk often increases because ophthalmic assessments can add:
This is not a reason to avoid ocular endpoints. It is a reason to plan them with retention in mind.
Practical retention-minded planning questions:
20/20 Onsite supports sponsors and CROs conducting clinical trials with ocular endpoints by providing end-to-end ophthalmic trial consultation, field execution, and single-call accountability.
From a retention standpoint, the key is reducing the burden without sacrificing protocol adherence. When ocular assessments can be delivered at the point of need, meaning where participants live, work, or congregate, travel friction drops, and missed visit risk often drops with it. That can help protect timelines and data continuity while reducing the burden on sites and coordinators.
Just as importantly, specialized ophthalmic execution needs to be consistent, standardized, and audit-ready. Retention gains do not help if data quality degrades. The retention-friendly approach is the one that keeps both sides true, participant experience, and protocol adherence.
Schedule a consultation with us to plan retention before dropout becomes a problem
If you want to reduce patient dropout rates in clinical trials, focus on these execution levers:
If your study includes complex visit schedules, hybrid elements, or ocular endpoints, now is the time to pressure test your protocol for retention risk.
Before First Patient In, we will review your draft protocol and map:
You will leave with a clear, sponsor-level retention risk brief, not generic advice, but specific adjustments that protect timelines, reduce replacement costs, and strengthen execution before attrition shows up in your weekly metrics.
Schedule a protocol review with our team to identify and remove friction before it becomes expensive.