Systematized Nomenclature of Medicine Clinical Terms ( SNOMED CT )

World Health Organization (WHO) level 1 is anatomical (organ or system) level 2 is therapeutic level 3 is pharmacological level 4 is chemical level 5 is the individual chemical substance • Developed to facilitate research by the WHO to improve the quality of drug use • ATC contains ingredients not used or available in the U.S.-Chemical structure-Pharmacological effects of drugs-Molecular Mechanism of pharmacologic action-Therapeutic uses • Controlled vocabulary for indexing, cataloging, and searching PubMed • Definitions of cancers, related diseases, cancer related medications, findings, and genes • Use case is cancer centric, and was therefore not evaluated further in this study • Separate drug hierarchies for-Physiological effects (PE)-Chemical structure (CHEM)-Mechanism of action (MoA) • NDF-RT harbors the EPC concepts-EPCs mapped to physiological effect, chemical structure, and mechanism of action • Disjoint hierarchies do not support a single hierarchy for EPC concepts-Not evaluated further in this study • Drug hierarchies-Pharmaceutical/biologic Product-Substance • Largest terminology with over 311,000 active concepts • Designated in the U.S. as the standard for electronic health information exchange and interoperability for many clinical domains, although not for medications