Document 0265
 DOCN  M9650265
 TI    A comparison of the temporal expressiveness of three database query
       methods.
 DT    9605
 AU    Das AK; Musen MA; Section on Medical Informatics, Stanford University
       School of; Medicine, California 94305-5479, USA.
 SO    Proc Annu Symp Comput Appl Med Care. 1995;:331-7. Unique Identifier :
       AIDSLINE MED/96123738
 AB    Time is a multifaceted phenomenon that developers of clinical
       decision-support systems can model at various levels of complexity. An
       unresolved issue for the design of clinical databases is whether the
       underlying data model should support interval semantics. In this paper,
       we examine whether interval-based operations are required for querying
       protocol-based conditions. We report on an analysis of a set of 256
       eligibility criteria that the T-HELPER system uses to screen patients
       for enrollment in eight clinical-trial protocols for HIV disease. We
       consider three data-manipulation methods for temporal querying: the
       consensus query representation Arden Syntax, the commercial standard
       query language SQL, and the temporal query language TimeLineSQL (TLSQL).
       We compare the ability of these three query methods to express the
       eligibility criteria. Seventy nine percent of the 256 criteria require
       operations on time stamps. These temporal conditions comprise four
       distinct patterns, two of which use interval-based data. Our analysis
       indicates that the Arden Syntax can query the two non-interval patterns,
       which represent 54% of the temporal conditions. Timepoint comparisons
       formulated in SQL can instantiate the two non-interval patterns and one
       interval pattern, which encompass 96% of the temporal conditions. TLSQL,
       which supports an interval-based model of time, can express all four
       types of temporal patterns. Our results demonstrate that the T-HELPER
       system requires simple temporal operations for most protocol-based
       queries. Of the three approaches tested, TLSQL is the only query method
       that is sufficiently expressive for the temporal conditions in this
       system.
 DE    Comparative Study  Decision Making, Computer-Assisted  *Information
       Storage and Retrieval  Information Systems  *Programming Languages
       Support, U.S. Gov't, Non-P.H.S.  Support, U.S. Gov't, P.H.S.  *Time
       JOURNAL ARTICLE

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       protected by Copyright Law (Title 17, U.S.Code).