Deterministic Radiographic Scoring in Inflammatory Arthritis: A Validator-Gated Architecture for Reproducible Endpoint Generation

Background: Radiographic scoring remains central to structural damage assessment in rheumatoid arthritis (RA), psoriatic arthritis (PsA), axial spondyloarthritis (axSpA), and related inflammatory conditions. Conventional visual scoring workflows are sensitive to inter-reader variability, calibration drift, and thresholding inconsistencies, limiting reproducibility in longitudinal monitoring and clinical trial endpoint generation—challenges that may be further exacerbated when AI-assisted tools operate as probabilistic 'black boxes' without explicit validation lineage.

Methods: We describe a deterministic, validator-gated radiographic analysis platform organized into two architectural layers: (1) a structured clinical rendering layer that produces standardized, anatomy-organized reports from validated descriptors, enforcing clinical purity through strict isolation from research-tier analytics; and (2) a research analytics layer deriving version-controlled endpoint measures from the same validated descriptor lineage. The platform enforces sequential validation gates addressing data integrity, descriptor completeness, projection adequacy, laterality verification and correction, symmetry normalization, and longitudinal eligibility when comparative scoring is requested. Schema-level safeguards prevent 'orphaned' quantitative statements, ensuring that longitudinal comparisons and composite integrations maintain structural and semantic completeness. All outputs include explicit operator and threshold version identifiers and audit-traceable provenance metadata.

Deterministic properties (by design): For identical validated descriptor inputs processed under the same operator and threshold versions, the system produces identical clinical renderings and endpoint fields. This architectural guarantee enables reproducible longitudinal scoring and version-stable exports suitable for multi-center research workflows and trial-oriented endpoint generation, subject to context-of-use validation for regulated submissions.

Conclusions: A validator-gated deterministic architecture offers a principled approach to reducing reader-dependent variability in radiographic scoring. By constraining downstream rendering and analytics to a controlled descriptor lineage with explicit versioning and audit traceability, the platform addresses key reproducibility challenges in current scoring methodologies and may provide a foundation for future regulatory-aligned endpoint generation in multi-center clinical trials, contingent on appropriate validation and qualification. Validation studies appropriate to the intended context of use remain required for any regulated endpoint application or clinical deployment.

Keywords: radiographic scoring; inflammatory arthritis; deterministic analytics; structured reporting; modified Total Sharp Score (mTSS); mSASSS; reproducibility; structural damage assessment; clinical trial endpoints; validator-gated architecture