8.1 Ethical Eligibility, Recruitment and Retention
Key Takeaways
Recruitment materials and methods should match the ethics-reviewed process.
Retention efforts must respect freedom to withdraw without penalty.
Recruitment and dropout metrics require contextual investigation rather than automatic conclusions.
Ethical Eligibility, Recruitment and Retention
Eligibility criteria serve scientific and safety purposes. The ethics committee evaluates the proposed population together with the protocol, consent, recruitment process and safeguards. A monitor should understand why a criterion exists, verify it from appropriate evidence and recognise when the site's recruitment practice undermines its purpose. Good recruitment reaches suitable people fairly; it does not relax criteria to improve site metrics.
A criterion may reduce a known risk, define the condition under study, support a reliable measurement or limit a confounding treatment. Distinguish these rationales from habitual exclusions that unnecessarily reduce representativeness. E6(R3) and the 2024 Declaration of Helsinki encourage appropriate representation and attention to the harms of exclusion. However, revising an unjustified restriction requires the authorised protocol/amendment process, not an individual monitor's waiver.
Examining an eligibility decision
Trace diagnosis, relevant history, laboratory or imaging evidence, timing, prohibited treatments and required investigator review. A checked box saying eligible is not enough when the supporting result is absent. Also distinguish a result obtained after enrolment from a result available before enrolment but filed later. The clinical and data consequences can differ, even though both situations need accurate records.
If evidence suggests an ineligible participant was enrolled, promptly involve the investigator and sponsor. The investigator evaluates care and the protocol's continuation/discontinuation rules; the sponsor assesses wider implications and reporting. The CRA documents the finding and follow-up without prescribing treatment or offering a retrospective exception. Do not infer that every eligibility error automatically removes all the participant's data from analysis.
Recruitment materials and methods
Review advertisements, referral scripts, social-media messages and participant-facing explanations as applicable. Compare actual material with the approved version and the process described to the IRB/IEC. Look for promises of cure, guaranteed benefit, misleading claims about payment, omission of meaningful burdens or pressure from a treating clinician. The recruitment process should make the research nature clear while allowing understandable, balanced information.
| Recruitment issue | Why it matters | Monitoring response |
|---|---|---|
| An obsolete advertisement promises a benefit absent from the current protocol | Potential misunderstanding and undue influence | Verify actual use, notify responsible staff and correct through the approved process |
| Staff pre-screen an unrelated patient list without appropriate access | Confidentiality risk | Establish permitted access and stop inappropriate use through the responsible functions |
| The site uses one language although its population needs others | Unfair access and poor comprehension | Assess translation/interpreter planning and approved materials |
| Completion payment dominates the message | Pressure to remain despite concerns | Check ethics-reviewed amount, method and schedule |
An accessible process can include suitable languages, understandable materials, reasonable scheduling and removal of unnecessary financial barriers. The same safeguards should reach remote participants, not only people visiting the clinic. A digital recruitment platform introduces access and privacy questions; outsourcing recruitment does not remove sponsor or investigator oversight.
Retention without pressure
Retention protects interpretability and can reduce missing data, but participants remain free to withdraw. Ask why people miss visits or stop participating: travel burden, treatment effects, inflexible scheduling, confusing instructions, technology problems or dissatisfaction with communication. Reasonable improvements may help, provided they remain within the protocol and reviewed process. For example, arranging an authorised visit option may be appropriate; inventing an unapproved home procedure is not.
Contact should be respectful and consistent with permission. Do not threaten loss of ordinary medical care, withhold earned prorated payment or repeatedly contact someone who has declined further contact. A participant need not provide a reason for withdrawal. Document what they choose and what follow-up, if any, they allow. Explain options without implying that continued research is required for care.
Interpreting recruitment and dropout metrics
An unusually high conversion rate can signal pre-screening methods, a genuinely suitable referral population, missing screen failures or improper enrolment. A high dropout rate can reflect disease progression, burden or site problems. Review denominators, eligibility complexity, exposure and data completeness before concluding misconduct or poor care. Metrics guide investigation rather than prove a cause.
For an illustrative feasibility estimate, a site sees 100 potentially relevant patients in a period. If 40 meet detailed criteria and half of those are realistically willing and able to participate, the estimated recruitment opportunity is 20, before considering competing trials and time limits. The arithmetic is 100 × 0.40 × 0.50 = 20. These are stated hypothetical inputs, not published CCRA benchmarks. The CRA should ask for the evidence supporting each assumption.
Track planned versus actual enrolment and reasons for nonparticipation while protecting privacy. Feed supported findings back into feasibility, participant communication and quality review. Successful recruitment means appropriate, voluntary participation with reliable follow-up, not simply a large randomisation total.
Official sources
Checked October 18, 2026: ICH E6(R3), Principles and Annex 1, WMA Declaration of Helsinki, 2024, ICH E11(R1).
A site proposes relaxing an exclusion criterion to meet recruitment targets. What should happen?
Enrol first and change the criteria date later.
Use a note to file instead of evaluating the change.
Use the authorised evaluation/amendment process; the site cannot independently waive the criterion.
Let the monitor approve it verbally.
Sections you finish are checked off in the contents.