Sequential result refinement for searching the biomedical literature.

Information overload is a problem for users of MEDLINE, the database of biomedical literature that indexes over 17 million articles. Various techniques have been developed to retrieve high quality or important articles. Some techniques rely on using the number of citations as a measurement of an article's importance. Unfortunately, citation information is proprietary, expensive, and suffers from "citation lag." MEDLINE users have a variety of information needs. Although some users require high recall, many users are looking for a "few good articles" on a topic. For these users, precision is more important than recall. We present and evaluate a method for identifying articles likely to be highly cited by using information available at the time of listing in MEDLINE. The method uses a score based on Medical Subject Headings (MeSH) terms, journal impact factor (JIF), and number of authors. This method can filter large MEDLINE result sets (>1000 articles) returned by actual user queries to produce small, highly cited result sets.

Sharable representation of clinical guidelines in GLIF: relationship to the Arden Syntax.

Clinical guidelines are intended to improve the quality and cost effectiveness of patient care. Integration of guidelines into electronic medical records and order-entry systems, in a way that enables delivery of patient-specific advice at the point of care, is likely to encourage guidelines acceptance and effectiveness. Among the methodologies for modeling guidelines and medical decision rules, the Arden Syntax for Medical Logic Modules and the GuideLine Interchange Format version 3 (GLIF3) emphasize the importance of sharing encoded logic across different medical institutions and implementation platforms. These two methodologies have similarities and differences; in this paper we clarify their roles. Both methods can be used to support sharing of medical knowledge, but they do so in complementary situations. The Arden Syntax is suitable for representing individual decision rules in self-contained units called Medical Logic Modules (MLMs), which are usually implemented as event-driven alerts or reminders. In contrast, GLIF3 is designed for encoding complex multistep guidelines that unfold over time. As a consequence, GLIF3 has several mechanisms for complexity management and additional constructs that may require overhead unnecessary for expressing simple alerts and reminders. Unlike the Arden Syntax, GLIF3 encourages a top-down process of guideline modeling consisting of three levels that are created in order: Level 1 comprises a human-readable flowchart of clinical decisions and actions. Level 2 comprises a computable specification that can be verified for logical consistency and completeness; and Level 3 comprises an implementable specification that includes information required for local adaptation of guideline logic as well as for mapping guideline variables onto institutional medical records. A major emphasis of the current GLIF3 development process has been to create the computable specification that formally represents medical decision and eligibility criteria. We based GLIF3's formal expression language on the Arden Syntax's logic grammar, making the necessary extensions to the Arden Syntax's data structures and operators to support GLIF3's object-oriented data model. We discuss why the process of generating a set of MLMs from a GLIF-encoded guideline cannot be automated, why it can result in information loss, and why simple medical rules are best represented as individual MLMs. We thus show that the Arden Syntax and GLIF3 play complementary roles in representing medical knowledge for clinical decision support.

MedlineQBE (Query-by-Example).

Medline has the potential to significantly improve medical care but effective information retrieval remains difficult. Custom interfaces and relevance feedback are two approaches that have been successfully used to improve information retrieval. There are, however, many ways to implement these approaches. A system that facilitates rapid implementation and evaluation of novel algorithms has the potential to speed research progress. This paper describes MedlineQBE, a research workbench for implementing and evaluating information retrieval strategies. User interface, database access and display of results are abstracted leaving developers with the task of coding only the algorithm of interest. We implemented several custom interfaces, search-refinement strategies and a result-ordering algorithm using MedlineQBE. Preliminary evaluations of an oncology-patient interface and a relevance feedback algorithm that builds upon PubMed's "related articles" feature are promising. We conclude that custom interfaces and novel relevance feedback strategies have the potential to improve information retrieval from Medline.

Guideline classification to assist modeling, authoring, implementation and retrieval.

The National Guideline Clearinghouse (NGC) and its guideline classification system are significant contributions to the study of clinical practice guidelines (CPGs) and their incorporation into routine clinical care. The NGC classification system is primarily designed to support guideline retrieval. We believe that a guideline classification system should also support identification of features that relate to incorporation of executable CPGs into computer-based applications for sharing and delivering guideline-based advice. We have developed a proposed expansion of the NGC guideline classification for this purpose. The axes of the proposed scheme have implications for designing formal models and structures for representing and authoring CPGs. This scheme also has implications for future research.

GLIF3: the evolution of a guideline representation format.

The Guideline Interchange Format (GLIF) is a language for structured representation of guidelines. It was developed to facilitate sharing clinical guidelines. GLIF version 2 enabled modeling a guideline as a flowchart of structured steps, representing clinical actions and decisions. However, the attributes of structured constructs were defined as text strings that could not be parsed, and such guidelines could not be used for computer-based execution that requires automatic inference. GLIF3 is a new version of GLIF designed to support computer-based execution. GLIF3 builds upon the framework set by GLIF2 but augments it by introducing several new constructs and extending GLIF2 constructs to allow a more formal definition of decision criteria, action specifications and patient data. GLIF3 enables guideline encoding at three levels: a conceptual flowchart, a computable specification that can be verified for logical consistency and completeness, and an implementable specification that can be incorporated into particular institutional information systems.