.jpg){kind=link}
- Published
- Updated
The people a trial aims to inform and the people a site can actually screen may differ. Eligibility criteria shape safety, interpretability and feasibility, rather than serving solely as a recruitment filter.
Define the question and assumptions
Create a rationale table connecting each exclusion to safety, measurement reliability or the scientific question. Define the intended population first, then examine who each criterion removes. A readily accessible sample should not automatically be treated as representative of everyone who might eventually use an intervention.
Hypothetical study example
In a hypothetical study, a frequently used concomitant medicine is excluded. An aggregate, deidentified feasibility review suggests many potential participants use it. The team revisits the clinical rationale and updates recruitment assumptions; it does not quietly change eligibility to improve a forecast.
Design review checks
- Record the rationale and verification source for every eligibility condition.
- Classify screening failures without counting the same person several times.
- Discuss how a restricted sample affects interpretation with the trial statistician.
Record the decision and its limits
Acceptance means that the owner, rationale and operational application of each criterion are clear. Any protocol amendment follows the applicable review process. Broader eligibility alone cannot resolve representation problems: visit burden, referral pathways and access barriers require separate consideration and evidence.
Frequently asked questions
- Does a screening log describe the target population?
- It describes people who reached screening; it does not directly describe those who never reached the site.
- Should every exclusion be removed?
- No. Preserve justified safety and scientific protections while challenging unexplained restrictions.