Letter: Further revamping VA's NDF-RT drug terminology for clinical research

Biomedical terminology and vocabulary standards (for the purposes of this correspondence , we use the terms 'terminology,' 'vocabulary' and 'ontology' interchangeably.) play an important role in enabling consistent, comparable, and meaningful sharing of data within and across institutional boundaries, as well as ensuring semantic interoperability. An important domain for developing standardized vocabularies is medications, where existing standards structure and organize approved drug products and ingredients by various characteristics or properties to support a multitude of clinical and epidemiological research questions across the spectrum of health and disease. Veteran Affairs' National Drug File-Reference Terminology (NDF-RT; see figure 1) is a Federal Medication recommended standardized terminology resource encompassing medications, ingredients , and high-level drug classes for Chemical relationship describing the Therapeutic Intent (eg, Pain), and Pharmacokinetics describing the mechanisms of absorption and distribution of an administered drug within a body (eg, Hepatic Metabolism). Additionally , NDF-RT contains two independent lists of drug classes: Legacy VA classes and External Pharmacologic classes, where the former simply provides a shallow hierarchy of 'clinically oriented' classes (eg, b blockers), and the latter focuses on classifying drugs based on their chemical properties and functional groups (eg, H1 Receptor Antagonist). In the recent past, several research reports have highlighted important issues and challenges in using NDF-RT for clinical research and interoperability. Bodenreider et al 1 focused on determining anticoagulation status of patients based on a list of medications prescribed using NDF-RT as the underlying drug-class terminology. In particular, this work concentrated on leveraging description logics (DL)-based representation of NDF-RT to infer additional information about drug-class relationships using the Legacy VA classes and External Pharmacologic classes. During this process, the authors not only had to make significant modifications and re-engineering to NDF-RT's DL representation, but also encountered several missing pieces of drug-class membership information in NDF-RT. In another study, Palchuk et al 2 constructed a hierarchy of NDF-RT drug classes with drug and medication information from another standardized drug terminology, RxNorm, using data from the patient's electronic medical record. Similar to Bodenreider et al, 1 here authors had to perform significant re-engineering to map, and subsequently classify , RxNorm drug products using Legacy VA classes from NDF-RT. The authors found this process to be extremely onerous, and proposed the evolution of RxNorm toward an interface terminology with hierarchical and categorical organization. In our own work published in JAMIA, 3 we investigated similar issues in mapping and classifying drugs and …