Recruiting and retaining participants is one of the most challenging—and most important—parts of running a successful clinical trial. Without enough qualified patients, trials may be delayed, underpowered, or never completed. High dropout rates can compromise data integrity, affect statistical significance, and increase operational costs.

This guide explores the biggest barriers to recruitment and retention and outlines proven strategies, tools, and metrics to help you boost participation and keep patients engaged through study completion.

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Why Recruitment and Retention Matter

More than 80% of clinical trials fail to meet their enrollment targets on time. Even after enrollment, retention is a major concern: participant dropouts can increase the risk of bias, reduce statistical power, and result in costly protocol deviations.

Recruitment and retention are directly linked to:

• Trial duration and operational efficiency
• Cost containment
• Data quality and completeness
• Regulatory approval

Planning for these elements from the outset—and tracking performance continuously—can help ensure success.

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Barriers to Recruitment

Understanding the root causes of low enrollment helps in designing targeted strategies:

• Lack of awareness: Many eligible patients never learn about trials
• Strict eligibility criteria: Overly narrow inclusion/exclusion rules limit reach
• Trust issues: Historical abuses and lack of transparency can create skepticism
• Logistical burdens: Time off work, travel, and caregiving responsibilities can make participation impractical
• Communication gaps: Language barriers and limited health literacy hinder comprehension and consent

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Recruitment Strategies That Work

Digital Advertising

• Use paid ads on platforms like Google, Facebook, and Instagram to reach specific demographics
• Drive traffic to IRB-approved landing pages with pre-screening forms

Physician Referrals

• Equip local clinicians with recruitment flyers, inclusion/exclusion summaries, and referral forms
• Build partnerships with specialists who regularly treat the target population

Community Engagement

• Partner with patient advocacy organizations, churches, schools, or local events
• Host informational sessions or webinars tailored to specific patient groups

EHR-Based Pre-Screening

• Leverage structured EHR data to flag eligible patients during routine care
• Implement alert systems that notify providers when patients match eligibility criteria

Patient Registries

• Use existing patient databases to identify and recontact eligible participants
• Offer registry opt-ins as part of ongoing care or previous studies

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Retention Challenges and How to Address Them

Even with strong enrollment, keeping participants engaged is critical:

• Visit fatigue: Long or frequent visits can cause participants to drop out
• Life disruptions: Personal, professional, or medical issues can interfere with study timelines
• Insufficient communication: Participants may feel disconnected or unsupported
• Perceived burden: Participants may not fully understand their impact on the research

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Retention Strategies That Work

Onboarding and Education

• Provide welcome kits, trial timelines, and easy-to-read onboarding materials
• Use video explainers or coordinator calls to set expectations and build rapport

Ongoing Communication

• Send appointment reminders and study updates via email, SMS, or app
• Offer 24/7 support lines or quick contact with site staff

Supportive Logistics

• Reimburse transportation, parking, lost wages, or childcare costs
• Offer home visits or telehealth check-ins for eligible activities
• Allow flexible scheduling, including evenings and weekends

Participant Engagement

• Use digital platforms to track symptoms, complete ePROs, and stay informed
• Share study progress and recognize participant milestones

Recognition and Gratitude

• Send thank-you notes, progress certificates, or small incentives to show appreciation
• Acknowledge the value of each participant’s contribution to science and future care

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Tools That Support Recruitment and Retention

• Recruitment platforms (e.g., Trialbee, Antidote) to manage ads and prescreening
• EHR-integrated flags to notify providers of eligible patients
• eConsent tools for fast, remote onboarding
• Communication platforms to automate reminders and updates
• EDC and CTMS dashboards to track enrollment and dropout rates across sites

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Metrics That Matter

• Time to first patient enrolled (FPI)
• Enrollment rate per site per month
• Screen failure rate
• Participant retention at key milestones
• Cost per enrolled and retained participant

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Real-World Examples

• A diabetes trial reached 1,200 pre-qualified leads in three weeks using targeted Facebook ads
• A decentralized oncology study achieved 92% retention by combining home health visits with 24/7 coordinator access
• A pediatric rare disease trial enrolled faster using multilingual outreach through parent advocacy groups and local clinics

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Key Takeaways

• Recruitment and retention are not side tasks—they are central to trial success
• Use digital, community, and provider channels to reach the right patients
• Design protocols and operations with participant convenience in mind
• Monitor performance metrics and adjust strategies in real time

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Frequently Asked Questions (FAQs)

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1. What’s a good retention rate for a 12-month study?
Over 85% is generally considered strong, though it varies by therapeutic area.

2. Can I use social media to recruit participants?
Yes, if the content is IRB-approved and complies with advertising guidelines.

3. How can I reduce screen failure rates?
Align your eligibility criteria with real-world patient data and use pre-screening tools to improve targeting.

4. Can EHR data be used to identify participants directly?
Yes, with appropriate privacy safeguards and site-level approvals.