Table Of ContentComputers and Medicine
Helmuth F. Orthner, Series Editor
Springer Science+Business Media, LLC
Computers and Medicine
Infonnation Systems for Patient Care
Bruce I. Blum (Editor)
Computer-Assisted Medical Decision Making, Volume 1
James A. Reggia and Stanley Tuhrim (Editors)
Computer-Assisted Medical Decision Making, Volume 2
James A. Reggia and Stanley Tuhrim (Editors)
Expert Critiquing Systems
Perry L. Miller
Use and Impact of Computers in Clinical Medicine
James G. Anderson and Stephen J. Jay (Editors)
Selected Topics in Medical Artificial Intelligence
Perry L. Miller (Editor)
Implementing Health Care Information Systems
Helmuth F. Orthner and Bruce I. Blum (Editors)
Nursing and Computers: An Anthology
Virginia K. Saba, Karen A. Rieder, and Dorothy B. Pocklington (Editors)
A ainical Information System for Oncology
John P. Enterline, Raymond E. Lendhard, Jr., and Bruce I. Blum (Editors)
HELP: A Dynamic Hospital Information System
Gilad J. Kuperman, Reed M. Gardner, and T. Allan Pryor
Decision Support Systems in Critical Care
M. Michael Shabot and Reed M. Gardner (Editors)
Infonnation Retrieval: A Health Care Perspective
William R. Hersh
William R. Hersh, M.D.
Biomedical Information Communication Center
Oregon Health Sciences University
Portland, Oregon
Information Retrieval:
A Health Care Perspective
With 59 Illustrations
Springer
William R. Hersh, M.D.
Associate Professor
Biomedical Information Communication Center
Oregon Health Sciences University
3181 SW Sam Jackson Park Road
Portland, OR 97201-3098, USA
Library of Congress Cataloging in Publication Data
Hersh, William R.
Infonnation retrieval: a health care perspective / by William R. Hersh.
p. cm. - (Computers and medicine)
Includes bibliographical references and index.
ISBN 978-1-4757-2531-5 ISBN 978-1-4757-2529-2 (eBook)
DOI 10.1007/978-1-4757-2529-2
1. Medical informatics. 2. Information storage and retrieval systems-Medicine. I. Title.
II. Series: Computers and medicine (New York, N.Y.)
R858.H47 1995
025.06'61--dc20 95-34175
CIP
Printed on acid-free paper.
© 1996 Springer Science+Business Media New York
Originally published by Springer-Verlag New York, Inc. in 1996
Softcover reprint of the hardcover 1s t edition 1996
All rights reserved. This work may not be translated or copied in whole or in part without the wrinen
permission of the publisher Springer Science+Business Media, LLC.
except for brief excerpts in connection with reviews or scholarly analysis. Use in connection
with any form of information storage and retrieval, electronic adaptation, computer software, or by
similar or dissimilar methodology now known or hereafter developed is forbidden.
The use of general descriptive names, trade names, trademarks, etc. in this publication, even if the
former are not especially identified, is not to be taken as a sign that such names, as understood by the
Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone.
While the advice and information in this book are believed to be true and accurate at the date of going
to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any
errors or omissions that may be made. The publisher makes no warranty, express or implied, with
respect to the material contained herein.
Production managed by Princeton Editorial Associates and supervised by Terry Kornak; manufacturing
supervised by Jacqui Ashri.
Typeset by Princeton Editorial Associates, Princeton, NJ.
9 8 7 6 5 4 3 2 I
ISBN 978-1-4757-2531-5
To Sally
Series Preface
This monograph series intends to provide medical infonnation scientists, health
care administrators, physicians, nurses, other health care providers, and computer
science professionals with successful examples and experiences of computer
applications in health care settings. Through the exposition of these computer
applications, we attempt to show what is effective and efficient and hope to
provide some guidance on the acquisition or design of medical infonnation sys
tems so that costly mistakes can be avoided.
The health care industry is currently being pushed and pulled from all direc
tions-from clinicians, to increase quality of care; from business, to lower cost
and improve fmancial stability; from legal and regulatory agencies, to provide
detailed documentation; and from academe, to provide data for research and
improved opportunities for education. Medical infonnation systems sit in the
middle of all these demands. The generally accepted (popular) notion is that these
systems can satisfy all demands and solve all the problems. Obviously, this notion
is naive and is an overstatement of the capabilities of current information technol
ogy. Eventually, however, medical information systems will have sufficient
functionality to satisfy most infonnation needs of health care providers.
We realize that computer-based information systems can provide more timely
and legible infonnation than traditional paper-based systems. Most of us know
that automated infonnation systems provide, on average, more accurate infonna
tion because data capture is more complete and automatic (e.g., directly from
devices). Medical information systems can monitor the process of health care and
improve quality of patient care by providing decision support for diagnosis or
therapy, clinical reminders for follow-up care, wamings about adverse drug inter
actions, alerts to questionable treatment or deviations from clinical protocols, and
more. Because medical infonnation systems are functionally very rich, must
respond quickly to user interactions and queries, and require a high level of
security, these systems can be classified as very complex and, from a developer's
perspective, also as "risky."
vii
viii Series Preface
Information technology is advancing at an accelerated pace. Instead of
waiting for 3 years for a new generation of computer hardware, we are now
confronted with new computing hardware every 18 months. The forthcoming
changes in the telecommunications industry will be revolutionary. Certainly
before the end of this century new digital communications technologies, such
as the Integrated Services Digital Network (ISDN) and very high-speed local
area networks using efficient cell switching protocols (e.g., ATM), will not
only change the architecture of our information systems but also the way we
work and manage health care institutions.
The software industry constantly tries to provide tools and productive develop
ment environments for the design, implementation, and maintenance of informa
tion systems. Still, the development of information systems in medicine is, to a
large extent, an art, and the tools we use are often self-made and crude. One area
that needs desperate attention is the interaction of health care providers with the
computer. Although the user interface needs improvement and the emerging
graphical user interfaces may form the basis for such improvements, the most
important criterion is to provide relevant and accurate information without drown
ing the physician in too much (irrelevant) data.
To develop an effective clinical system requires an understanding of what is to
be done and how to do it and an understanding of how to integrate information
systems into an operational health care environment. Such knowledge is rarely
found in anyone individual; all systems described in this monograph series are the
work of teams. The size of these teams is usually small, and the composition is
heterogeneous (i.e., health professionals, computer and communications scientists
and engineers, biostatisticians, epidemiologists, etc). The team members are usu
ally dedicated to working together over long periods of time, sometimes spanning
decades. Clinical information systems are dynamic systems; their functionality
constantly changes because of external pressures and administrative changes in
health care institutions. Good clinical information systems will and should change
the operational mode of patient care, which, in tum, should affect the functional
requirements of the information systems. This interplay requires that medical
information systems be based on architectures that allow them to be adapted
rapidly and with minimal expense. It also requires a willingness by management
of the health care institution to adjust its operational procedures and most of all, to
provide end-user education in the use of information technology. Although medi
cal information systems should be functionally integrated, these systems should be
modular so that incremental upgrades, additions, and deletions of modules can be
done to match the pattern of capital resources and investments available to an
institution.
We are building medical information systems just as automobiles were built
early in this century (191Os) (Le., in an ad hoc manner that disregarded even
existing standards). Although technical standards addressing computer and com
munications technologies are necessary, they are insufficient. We still need to
develop conventions and agreements, and perhaps a few regulations, that address
the principal use of medical information in computer and communication systems.
Series Preface ix
Standardization allows the mass production of low-cost parts that can be used to
build more complex structures. What are these parts exactly in medical informa
tion systems? We need to identify them, classify them, describe them, publish their
specifications, and, most important, use them in real health care settings. We must
be sure that these parts are useful and cost-effective even before we standardize
them.
Clinical research, health services research, and medical education will benefit
greatly when controlled vocabularies are used more widely in the practice of
medicine. For practical reasons, the medical profession has developed numerous
classifications, nomenclatures, dictionary codes, and thesauri (e.g., lCD, CPT,
DSM-ill, SNOWMED, COSTAR dictionary codes, BAlK thesaurus terms, and
MESH terms). The collection of these terms represents a considerable amount of
clinical activity, a large portion of the health care business, and access to our
recorded knowledge. These terms and codes form the glue that links the practice
of medicine with the business of medicine. They also link the practice of medicine
with the literature of medicine, with further links to medical research and educa
tion. Because information systems are more efficient in retrieving information
when controlled vocabularies are used in large databases, the attempt to unify and
build bridges between these coding systems is a great example of unifying the
field of medicine and health care by providing and using medical informatics
tools. The Unified Medical Language System (UMLS) project of the National
Library of Medicine, NIH, in Bethesda, Maryland, is an example of such effort.
The purpose of this series is to capture the experience of medical informatics
teams that have successfully implemented and operated medical information sys
tems. We hope the individual books in this series will contribute to the evolution
of medical informatics as a recognized professional discipline. We are at the
threshold where there is not just the need but already the momentum and interest
in the health care and computer science communities to identify and recognize the
new discipline called Medical Informatics.
HELMUTH F. ORTHNER
Washington, DC
Preface
The main goal of this book is to provide an understanding of the theory, im
plementation, and evaluation of information retrieval (IR) systems in the health
care field. There are already a number of excellent "how-to" volumes on searching
health care databases (Feinglos, 1985; Albright, 1988; Williams et al., 1992).
Likewise, there are also a number of excellent basic IR textbooks (Salton, 1983;
Harter, 1986; Pao, 1989; Meadow, 1992; Lancaster & Warner, 1993). This volume
is different from any of the above in that it covers basic information retrieval like
the latter volumes, but with a distinct focus on the health care domain.
The approach taken is to introduce all the necessary theory to allow coverage of
the implementation and evaluation of IR systems. Any book on theoretical aspects
must necessarily use technical jargon, and this book is no exception. I aim to
minimize that jargon but cannot eliminate it without retreating to a more super
ficial level of coverage. Understanding of the jargon will vary among readers
based on background, but anyone with some background in computers, libraries,
or medicine should be able to understand most of the terms used. In any case, an
attempt to define all such terms is made.
Another approach used is to classify topics wherever possible, whether discuss
ing types of information or models of evaluation. I have always found classifica
tion useful in providing an overview of complex topics. One problem, of course, is
that everything does not fit into the neat and simple categories of the classification.
This occurs repeatedly with information science, and the reader is forewarned, but
I still feel the effort is worth it.
This book had its origins in a tutorial taught at the annual Symposium on
Computer Applications in Medicine (SCAMC) meeting. The details emerged from
the syllabus of a course taught jointly in the Medical Informatics Training Program
at Oregon Health Sciences University and the Department of Computer Science at
Portland State University. Thus, the book could be used in either a basic informa
tion science course or a health information science course. It should also provide a
strong background for others interested in this topic, including those who design,
implement, use, and evaluate IR systems.
xi
xii Preface
Interest in medical text retrieval systems is increasing. I entered a fellow
ship in medical informatics at Harvard University in the late 1980s. I had
assumed I would take up the banner of some aspect of medical artifical
intelligence, such as knowledge representation. But along the way I came
across a reference from the field of "information retrieval." It looked inter
esting, so I looked at the references within that reference. It did not take
long to figure out that this was where my real interests lay, and I spent many
an afternoon in my fellowship tracing references in the Harvard and MIT
libraries. Even though I had not yet heard of the field of bibliometrics, I was
personally validating all its principles.
There is also an increasing need for better text retrieval systems. Writing on the
future of internal medicine and the need for it to return to its generalist roots,
Fletcher and Fletcher (1993) have said:
Computerized information is another technologic change that will reduce the need
for the kinds of highly specialized physicians who now comprise a large proportion
of the medical workforce, especially in internal medicine. An important role for
subspecialists today is to carry and dispense complex information .... In the future,
such information will be readily available from computerized sources. So far, com
puters have not had much"effect on day-to-day clinical decision making because
most physicians are unused to them; present-day computers are usually stationary
(on a desk top) whereas physicians move about, and the computers do not contain
much clinically useful information in a readily accessible form. New generations of
computers, soon to be available, will access vast amounts of information, sort it in a
user-friendly fashion, and make it available at the bedside and in the clinic.
The book is divided into four sections. The first section covers the basic
concepts of information science. The first chapter provides basic defmitions and
models that will be used throughout the book. The next chapter gives an overview
of medical information, covering issues related to its generation and use. The third
chapter discusses the evaluation of information retrieval systems, highlighting the
methods and their limitations. The evaluation chapter is deliberately placed at the
beginning of the book to emphasize the fundamental importance of this topic.
The second section covers the current state of the art in commercial and other
widely used retrieval systems. The first chapter in this section gives an overview
of many of the databases that are currently available. Next come chapters on the
two fundamental components of information retrieval, indexing and retrieval, in
which the predominant paradigms of each are discussed in detail. The final chapter
covers evaluation of these systems, providing a justification for the work described
in the following section on research efforts.
The third section covers the major threads of research and development in
efforts to build better retrieval systems. The focus is initially on details of
indexing and retrieval, with a chapter each on the two major thrusts, which are
word-statistical and linguistic systems. In the next chapter, a survey of various
efforts to enhance existing systems by assisting the user is described, including the
use of artificial intelligence methods. Throughout this section, a theme of im
plementational feasibility and evaluation is maintained.
