Eligibility Rule Engine

The engine applies Boolean logic (AND, OR, NOT) and comparison operators (=, >, <, ≥, ≤) to patient facts with absolute reproducibility. Unlike probabilistic AI models, a deterministic engine guarantees the same input always yields the same output—critical for regulatory audit trails.

• Evaluates atomic criteria like Hemoglobin >= 9.0 g/dL or Diagnosis == 'Non-Small Cell Lung Cancer'
• Supports nested logic groups for complex compound criteria
• Produces a definitive PASS, FAIL, or INCONCLUSIVE (insufficient data) result per criterion

The engine validates time-window constraints against a patient's longitudinal record to enforce criteria like washout periods, disease progression timelines, and recency requirements.

• Evaluates constraints such as Prior chemotherapy completed > 28 days before enrollment
• Reconstructs clinical event sequences from timestamped data points
• Handles relative time offsets (e.g., within 6 months of diagnosis) and absolute date thresholds
• Flags violations of minimum or maximum interval requirements between events

The engine maps clinical concepts to standardized terminologies (SNOMED CT, LOINC, RxNorm, ICD-10-CM) before evaluation, ensuring that synonymous expressions are consistently interpreted.

• Normalizes high blood pressure and essential hypertension to the same SNOMED concept
• Converts lab values to consistent units (e.g., mg/dL vs. mmol/L) before comparison
• Resolves medication synonyms to RxNorm ingredient-level concepts for concomitant medication checking
• Eliminates false negatives caused by terminology mismatch

Complex, multi-part eligibility criteria are automatically decomposed into atomic, independently evaluable units before execution. This enables granular pass/fail tracking and clear screen failure reporting.

• Parses a criterion like Histologically confirmed NSCLC, Stage IIIB-IV, with ECOG 0-1 into three separate evaluable facts
• Maintains parent-child logical relationships between decomposed atoms
• Enables partial matching and weighted scoring when full criteria cannot be met
• Supports criteria weighting to prioritize critical inclusion factors over secondary ones

Every eligibility decision is accompanied by a complete, immutable decision trace that records which patient facts were evaluated, which criteria passed or failed, and why.

• Logs the exact patient value compared against each criterion threshold
• Provides a human-readable justification for every FAIL result (e.g., Hemoglobin 8.2 g/dL < required 9.0 g/dL)
• Supports regulatory compliance with 21 CFR Part 11 audit trail requirements
• Enables rapid screen failure analysis and protocol refinement

The engine supports versioned rule libraries that automatically detect and integrate changes from formal protocol amendments without requiring full system redeployment.

• Maintains distinct rule sets for each protocol version with effective dates
• Automatically applies the correct version based on the patient's screening date
• Provides diff reports showing exactly which criteria were added, removed, or modified
• Ensures continuity of screening operations during protocol transitions