Stuart J. Nelson

Relationships in Medical Subject Headings (MeSH)

Recent efforts to make some of the relationships within MeSH more explicit have led to a deeper understanding of the nature of these relationships. This chapter will explore the relationships represented in MeSH in the light of that understanding. Every term that occurs may be thought of as representing a concept. One or more terms, comprising one or more concepts, grouped together for important reasons, form a descriptor class. The descriptor class is the basic building block of the thesaurus. Relationships among concepts can be represented explicitly in the thesaurus, most notably as relationships within the descriptor class. Hierarchical relationships are at the level of the descriptor class. The hierarchies are key in allowing expanded retrievals. The hierarchical relationships, traditionally thought of as broader or narrower (parent-child) relationships, are better understood as representing broader and narrower retrieval sets. Nevertheless, these hierarchical relationships often reflect important broader-narrower relationships between preferred concepts in descriptor classes. Other types of relationships present in the thesaurus include associative relationships, such as the Pharmacologic Actions or see-related cross references, as well as forbidden combination expressions, such as the Entry Combination.

Normalized names for clinical drugs: RxNorm at 6 years.

OBJECTIVE In the 6 years since the National Library of Medicine began monthly releases of RxNorm, RxNorm has become a central resource for communicating about clinical drugs and supporting interoperation between drug vocabularies. MATERIALS AND METHODS Built on the idea of a normalized name for a medication at a given level of abstraction, RxNorm provides a set of names and relationships based on 11 different external source vocabularies. The standard model enables decision support to take place for a variety of uses at the appropriate level of abstraction. With the incorporation of National Drug File Reference Terminology (NDF-RT) from the Veterans Administration, even more sophisticated decision support has become possible. DISCUSSION While related products such as RxTerms, RxNav, MyMedicationList, and MyRxPad have been recognized as helpful for various uses, tasks such as identifying exactly what is and is not on the market remain a challenge.

RxNorm: prescription for electronic drug information exchange

Commercial drug information systems follow a variety of naming conventions. A smooth electronic exchange of the information in these systems - not only between organizations but even within a single organization - is crucial in assuring patient safety. This exchange requires a standardized nomenclature. To meet this need, the National Library of Medicine (NLM) created RxNorm, a standardized nomenclature for clinical drugs that is one of a suite of standards designated for use in US federal government systems for the electronic exchange of clinical health information.

Demyelinating neuropathy accompanying Lyme disease

Lyme disease is characterized by skin, joint, heart, and central or peripheral neurologic disease. We studied a patient with typical Lyme disease, including a demyelinating neuropathy, who had many characteristics of the Guillain-Barré syndrome, although it was accompanied by CSF pleocytosis. Immunologic abnormalities occurring in Lyme disease suggest immune pathogenesis of the peripheral demyelination.

Integrating SNOMED CT into the UMLS: An Exploration of Different Views of Synonymy and Quality of Editing

OBJECTIVE The integration of SNOMED CT into the Unified Medical Language System (UMLS) involved the alignment of two views of synonymy that were different because the two vocabulary systems have different intended purposes and editing principles. The UMLS is organized according to one view of synonymy, but its structure also represents all the individual views of synonymy present in its source vocabularies. Despite progress in knowledge-based automation of development and maintenance of vocabularies, manual curation is still the main method of determining synonymy. The aim of this study was to investigate the quality of human judgment of synonymy. DESIGN Sixty pairs of potentially controversial SNOMED CT synonyms were reviewed by 11 domain vocabulary experts (six UMLS editors and five noneditors), and scores were assigned according to the degree of synonymy. MEASUREMENTS The synonymy scores of each subject were compared to the gold standard (the overall mean synonymy score of all subjects) to assess accuracy. Agreement between UMLS editors and noneditors was measured by comparing the mean synonymy scores of editors to noneditors. RESULTS Average accuracy was 71% for UMLS editors and 75% for noneditors (difference not statistically significant). Mean scores of editors and noneditors showed significant positive correlation (Spearmans rank correlation coefficient 0.654, two-tailed p < 0.01) with a concurrence rate of 75% and an interrater agreement kappa of 0.43. CONCLUSION The accuracy in the judgment of synonymy was comparable for UMLS editors and nonediting domain experts. There was reasonable agreement between the two groups.

DrugCentral: online drug compendium

DrugCentral (http://drugcentral.org) is an open-access online drug compendium. DrugCentral integrates structure, bioactivity, regulatory, pharmacologic actions and indications for active pharmaceutical ingredients approved by FDA and other regulatory agencies. Monitoring of regulatory agencies for new drugs approvals ensures the resource is up-to-date. DrugCentral integrates content for active ingredients with pharmaceutical formulations, indexing drugs and drug label annotations, complementing similar resources available online. Its complementarity with other online resources is facilitated by cross referencing to external resources. At the molecular level, DrugCentral bridges drug-target interactions with pharmacological action and indications. The integration with FDA drug labels enables text mining applications for drug adverse events and clinical trial information. Chemical structure overlap between DrugCentral and five online drug resources, and the overlap between DrugCentral FDA-approved drugs and their presence in four different chemical collections, are discussed. DrugCentral can be accessed via the web application or downloaded in relational database format.

Evaluating RECONSIDER: a computer program for diagnostic prompting

RECONSIDER, a computer program designed to perform as a diagnostic prompting aid, was evaluated for its ability to include the correct diagnosis in an ordered computed list of candidate diseases. The study was performed using 100 consecutive first admissions to the medical service of a university hospital, where the individuals entering the data into the program were blind to all but a limited set of findings known at time of admission. Each person entering the data created one or more lists of diagnostic possibilities (versions) using the program. The program suggested the correct diagnosis within the first 40 on its list 61% (498/797) of the time; the correct diagnosis was present with the first 40 in at least one version 93% (98/105) of the time. Performance was found to be best with cases having a single diagnosis and when more terms were entered into the program.

Orthopaedic Literature and MeSH

BackgroundSince 1916 there has been a recognized demand for a method of classification of orthopaedic literature inclusive enough to permit the proper collection and retrieval of all literature on the subject. Today, MEDLINE, available through the PubMed interface, has become the de facto standard for organization and retrieval of medical literature. The Medical Subject Headings (MeSH), used to provide indexing and assist in searching, are partly responsible for this standard. Understanding how MeSH is built and maintained may lead the user to a better understanding of how to use MEDLINE, and what to expect from the indexing of an article.Questions/purposesThe purpose of this review is to provide an understanding of the organization of large quantities of indexed material, the indexing process and the considerations involved in developing an indexing vocabulary.Where are we now?Successful terminology development and use, a prerequisite for any sharing of information by electronic means, depends on both user (how the user is expected to use the system) and information (how the information is organized) models. MEDLINE has a simple user model and a simpler information model. The user is expected to determine what is relevant and which MeSH descriptors are appropriate.Where do we need to go?While MEDLINE through PubMed is a success as viewed by the number of hits, further improvements will depend on better, faster indexing with a controlled terminology. Terminology development requires careful consideration of the nature of the subject, how users employ the terminology, the overall purpose of the terminology, and the framework of the systems in which it is used.How do we get there?For the future, understanding terminology development might enable the user to comprehend some of the issues involved in sharing of other information by electronic means. Further improvements in the availability and accessibility of medical literature will depend on continued maintenance and development of MeSH, as well as on refinement of the indexing process.

Building a Standards-Based and Collaborative E-Prescribing Tool MyRxPad

MyRxPad is a prototype application developed at the National Library of Medicine that helps prescribers lower some of the e-prescribing adoption barriers and encourages an early positive experience of e-prescribing. We envision a practitioner-patient collaborative approach towards e-prescribing: patients play an active role in their healthcare by maintaining up-to-date and accurate medication lists. Prescribers make well-informed and safe prescribing decisions based on personal medication records contributed by patients. In the paper, we discuss the development of MyRxPad, a vehicle for collaborations with patients using MyMedicationList. Integration with personal medication records in the context of e-prescribing is thus enabled. An early version of MyRxPad is available at http://rxp.nlm.nih.gov.

Making the most of reconsider: an evaluation of input strategies

During the performance of an evaluation of a diagnostic proupting program, RECONSIDER, on consecutive first admissions at a tertiary care hospital, the question arose if there were input strategies which insured better performance of the program. The program generates differential diagnoses from patient findings by comparing these findings to disease descriptions in its library. The patient data may be entered under a general or under specific contexts. All positive findings were abstracted for each case and used as a source of input data. Each case was entered by seven different users who were free to choose which items to enter and under what context to enter them. Each program run generated a ranked differential diagnosis list, and the rank number of the actual diagnosis was defined as the score for that run. Nonparairie-tric, multiple regression analysis, and defined strategy evaluations of the multiple versions of each case were performed. An optimal strategy for input remains to be determined; the ability to use various options seems to be important.