Abstract
OBJECTIVES: The objectives of this study were to: (1) explore and analyze the structure and content of 19 SNOMED Clinical Terms (SNOMED CT) national editions; (2) identify overlaps and types of quality issues; and (3) offer recommendations to improve the quality of these national editions. MATERIALS AND METHODS: We used expression constraint language and structured query language to analyze and compare the national editions hosted on the SNOMED International SNOMED CT Browser and the International and Canadian Edition Release Format Two files. RESULTS: The 19 national editions authored over 275 000 concepts and over 2.1 million descriptions. Modules were used to organize drug extensions, language translations, patient-friendly descriptions, maps, and subsets. The national editions included 27 languages and dialects reference sets, maps to international, national, and local terminologies, and over 1100 subsets. Since 2012, over 28 000 extensions have been promoted to the International Edition. Overlaps were also identified between national editions. DISCUSSION: Challenges of extensions included inconsistent modeling of concepts and quality issues, versioning and maintenance, and risks to semantic interoperability and data analysis. We suggest improved functionality in authoring tools to identify overlapping content across national editions and the incorporation of auditing methods to ensure high-quality extensions, increased collaboration between countries, and the accelerated harmonization of extensions into the International Edition. CONCLUSION: Nineteen countries have developed over 2.4 million extension concepts and descriptions, and it is important to harmonize the national editions through ongoing collaboration to maintain the integrity and consistency of SNOMED CT as a global reference terminology.