Transforming Triage Assessment Questions Into a Set of Standardized Clinical Concept Statements and Coding with SNOMED CT

Authors

David A. Thompson, Northwestern University, Northwestern University Feinberg School of Medicine

Eric Rose, Department of Biomedical Informatics and Medical Education, University of Washington School of Medicine.

Background: Telephone (telehealth) triage enables nurses to assess symptoms, determine urgency, and guide patients to appropriate care. Each telehealth triage guideline includes Triage Assessment Questions (TAQs) that serve as both an assessment script and decision-support tool for the triager. Each TAQ contains clinical text (e.g., fever over 104, severe abdominal pain) for which the triager seeks a Yes / No response. The TAQs are sorted in descending urgency level and by a Recommended Disposition Level—ranging from emergency intervention (e.g., Call 911) to Self-Care at Home. The goal of this study was to determine whether TAQs could be systematically restated as a set of proprietary Clinical Concepts (CC) chained together using Boolean logic, and whether those CCs could be coded with SNOMED CT to enhance standardization and interoperability, while identifying gaps in SNOMED CT coverage. 

Methods: The study focused on active adult after-hours triage guidelines, in which TAQs were initially transformed into expressions consisting of standardized proprietary CCs joined in Boolean expressions to establish structured relationships between symptoms and clinical dispositions. For example, a TAQ stating, “HIV positive or severe immunodeficiency (severely weak immune system) AND dirty cut” was transformed into the Boolean expression A AND (B OR C), where: A: Wound dirty or caused by a dirty object (ConceptID 3684), B: HIV positive (ConceptID 130), C: Severe immunodeficiency (Concept ID 131). Each CC was then coded using SNOMED CT; each SNOMED CT to CC map could be an Exact Match, Broader (SNOMED CT concept was semantically broader than the CC), Narrower, or Null (No SNOMED CT reasonably semantically close to CC). For example, SNOMED code 247373008 (Ankle pain) is broader than Concept ID 5956 (Severe ankle pain); and, SNOMED code 21522001 (Abdominal pain) is an exact match for Concept ID 3679 (Abdomen pain). All CC transformations and subsequent SNOMED CT coding were performed by an experienced physician clinical terminologist.

Results: The study analyzed 434 active adult after-hours triage guidelines, encompassing 11,005 TAQs (9,157 excluding TAQs that re-direct triager to a different guideline). Of these, 10,888 TAQs (98.9%) were assigned CCs, using 5,884 unique concepts. SNOMED CT coding resulted in 1,492 unique SNOMED CT codes mapped to these CCs. Mapping of SNOMED CT to Clinical Concept resulted in 1,878 (17.2%) exact matches, 7,004 broader matches (64.3%). Mapping resulted in 2,006 null matches (18.4%). These findings demonstrate that TAQs can be effectively transformed into standardized CCs using Boolean logic, creating a structured framework for triage decision-making. The successful mapping of most concepts to SNOMED CT supports the feasibility of integrating this method into clinical informatics systems while also revealing mapping limitations and areas needing terminology expansion.

Conclusion: This study demonstrates that transforming TAQs into standardized Clinical Concepts using Boolean logic is a viable approach to structuring telehealth triage decision-making. The high proportion of broader SNOMED CT matches indicates that while existing terminology supports most triage concepts, refinements are necessary to achieve greater specificity. The presence of null mappings highlights gaps in standardized coding, suggesting opportunities for expansion in SNOMED CT coverage. Addressing these limitations will be critical for enhancing interoperability, improving nurse decision-support tools, and ensuring consistent triage assessments. Future research should focus on refining Boolean logic formulations, optimizing SNOMED CT mappings, and expanding terminological frameworks to strengthen telehealth triage systems and their clinical application

Citation

Rose E, Thompson DA. Transforming Triage Assessment Questions Into a Set of Standardized Clinical Concept Statements` and Coding with SNOMED CT. June 7, 2025.