A S.C.O.R.E. framework for evaluating open-ended responses from large language models in healthcare.

Domain-specific evaluation is essential for clinical validation. We propose S.C.O.R.E. (Safety, Consensus & Context, Objectivity, Reproducibility, Explainability), a five-dimensional framework for structured expert evaluation of LLM-generated healthcare responses. S.C.O.R.E. has been validated against quantitative metrics (BLEU, ROUGE, and BERTScore) using three LLMs (GPT-4o, Claude 4 Sonnet, and DeepSeek) across ophthalmology, medication, and anesthesia. While quantitative metrics frequently misclassified clinically appropriate responses as inaccurate, S.C.O.R.E. demonstrated acceptable internal consistency (Cronbach's α 0.745) in the hyperparameter-optimized domain and detected large effect sizes (Cliff's δ 0.68-0.92) reflecting optimization status. Model rankings reversed across specialties-GPT-4o excelled in ophthalmology (optimized domain), while others in non-optimized domains-thus domain-specific tuning is both necessary and detectable through expert evaluation. S.C.O.R.E.'s correlation between framework reliability and optimization status validates its utility for iterative model refinement. This structured approach enables practical clinical validation, providing actionable feedback for developers and supporting regulatory compliance through standardized documentation of safety, evidence alignment, and explainability.