Trial Design
Inclusion / Exclusion Criteria
Inclusion and exclusion criteria are the protocol-defined conditions a person must satisfy (inclusion) or not exhibit (exclusion) to be eligible to enroll in a clinical trial.
Eligibility criteria balance scientific homogeneity against operational feasibility and external validity. Each additional criterion narrows the eligible population, often non-linearly; Tufts CSDD analyses show that the median Phase III oncology protocol has 35 eligibility criteria, and removing the lowest-yield 10% typically increases the eligible pool by 30; 60% with negligible effect on outcome interpretation.
Common over-restriction patterns: arbitrary lab thresholds without medical justification, narrow age windows, exclusion of well-controlled comorbidities, prohibition of common concomitant medications, and washout periods longer than the half-life of the prohibited drug.
AI-assisted protocol review (Kitsa KScribe) parses each criterion, estimates its impact on the eligible pool against real-world EHR data, and flags those with high recruitment cost and low scientific value before the protocol is finalized.
Related terms
Clinical Trial Protocol
A clinical trial protocol is the master document that defines a clinical study's objectives, design, methodology, statistical considerations, and operational conduct, and that all investigators must follow to ensure scientific validity and participant safety.
Patient Pre-screening
Patient pre-screening is the process of evaluating individuals against a clinical trial's inclusion and exclusion criteria, before formal screening visits, to identify likely-eligible candidates and reduce screen failure rates.
Screen Failure Rate
The screen failure rate is the percentage of patients who consent to be screened for a clinical trial but are subsequently found ineligible and not randomized.
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