Health Information Technology Standards

Series Editor: Tim Benson

Tim Benson

Principles of Health Interoperability HL7 and SNOMEDSecond Edition

Tim BensonAbies LtdHermitage, ThatchamBerkshireUK

ISBN 978-1-4471-2800-7 2nd edition ISBN 978-1-4471-2801-4 2nd edition (eBook)ISBN 978-1-84882-802-5 1st edition ISBN 978-1-84882-803-5 1st edition (eBook)DOI 10.1007/978-1-4471-2801-4Springer Dordrecht Heidelberg New York London

Library of Congress Control Number: 2012937362

British Library Cataloguing in Publication DataA catalogue record for this book is available from the British Library

Springer-Verlag London 2012This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifi cally the rights of translation, reprinting, reuse of illustrations, recita-tion, broadcasting, reproduction on microfi lms or in any other physical way, and transmission or infor-mation storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifi cally for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publishers location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law.The use of general descriptive names, registered names, trademarks, service marks, etc. in this publica-tion does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.While the advice and information in this book are believed to be true and accurate at the date of publica-tion, 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.

Printed on acid-free paper

Springer is part of Springer Science+Business Media (www.springer.com)

This book is dedicated to my sons Laurence, Oliver, Alex, and Jamie.

vii

Foreword to the First Edition

Health data standards are a necessary component of interoperability in health care. Aggregation of health-related data mandates the use of standards, and aggregation is necessary to support safe and quality care. The American Recovery and Reinvestment Act (ARRA) includes $19 billion dollars in direct funding and an additional $18.5 billion in returned savings tagged to the use of health information technology (HIT). The resulting expanding use of HIT has engaged a growing num-ber of stakeholders, many of whom now realize the value of standards.

All aspects of creating and meaningful use of electronic health records (EHRs) require standards. With the increasing demand for individuals knowledgeable in what standards are available and how and when to use those standards, this book is most welcome. The author, Tim Benson, has been engaged in the creation of standards since the beginning. His experiences span organizations including HL7, CEN, and ISO and terminologies such as SNOMED and LOINC. He has engaged the global com-munity and understands similarities as well as differences among the global community. He has a top reputation as a teacher and writer within the international community. I know no other individual more qualifi ed to write this book than Tim Benson.

In Principles of Health Interoperability HL7 and SNOMED , Tim focuses on major contributors to the set of required standards. In the fi rst section, he lays out a framework for why interoperability is important and what is needed to accomplish that interoperability. Health Level Seven (HL7) is preeminent among the several contributing Standards Developing Organizations (SDOs) in the global community. HL7 standards are widely used and cover the full spectrum of applications. Its mem-bership is international (currently including over 35 countries) and includes the major HIT vendors and representatives of the full set of stakeholders. The International Healthcare Technology Standards Developing Organization (IHTSDO) is rapidly promoting SNOMED CT as the preferred terminology in health care. While focusing on HL7 and SNOMED CT, Tim has included much useful informa-tion on other standards and other organizations.

Readers will fi nd this book easy to read, even if it is their fi rst exposure to stan-dards. In this rapidly changing fi eld, this book is a must for anyone who is involved or has interest in the use of health information technology and who isnt.

ix

Foreword to the Second Edition

The success of this book validates the above remarks. Interoperability and the focus of the broad community on this topic and the implementation of systems and stan-dards that support interoperability have grown at an exponential rate. As the imple-mentation of Health Information Interchange systems grows, more and more people join the workforce to support this growth. They need to be taught and learn about standards supporting interoperability. I and a number of colleagues use this book as a text. The students love it it is clear and easy to read and understand. Technology and the ensuing standards to support standards change rapidly. In this second addi-tion, Tim has astutely addressed this challenge. In some sections, he expanded the material; in others he reorganized the material; and, most importantly, he added new sections to increase the comprehension and coverage of the topic. The second edi-tion is even better than the fi rst.

Durham, NC, USA W. Ed Hammond, Ph.D.Director, Duke Centre for Health Informatics

Duke Translational Medicine Institute Duke University

Associate Director, Biomedical Informatics Core Duke Translational Medicine Institute

Professor, Community and Family MedicineDuke University

Founding Member of HL7 (1987), Chair HL7 (1991,19961997, 20082009)

xi

Preface

Health information technology (HIT) promises to deliver the right information at the right time and the right place. Everybody (patient, clinician, manager, and payer) stands to benefi t from more soundly based decisions, safer care, and less waste, errors, delays, and duplicated efforts.

This depends on us using computers to share information and make it available when and where it is needed in a way that meets privacy requirements. We need to use appropriate standards to link systems together within and across organizations.

Health Level Seven (HL7) and SNOMED CT are two of the key international standards, which underpin efforts to improve healthcare interoperability. HL7 pro-vides the structure, rather like English grammar, while SNOMED CT provides words that computers can understand.

This book provides an introduction to healthcare interoperability in general, and these standards in particular, setting out the core principles in a clear readable way for analysts, students, and clinicians to understand.

The second edition of this book has been completely revised and extended by four chapters, with new chapters on Privacy and IHE XDS (Cross-Enterprise Document Sharing), clinical coding schemes, and the SNOMED Concept Model.

The book is organized in three parts. The fi rst part covers the principles of health-care interoperability, why it matters, why it is hard, and why modeling is an impor-tant part of the solution. The second part covers the main HL7 standards: Version 2, Version 3, and CDA standards and related IHE profi les. The third part covers clini-cal terminology and SNOMED CT.

xiii

Series Preface

In every industry, and healthcare is no exception, standards are the key to reuse, trust, and interoperability, leading to cost reduction and quality improvement. In healthcare, having information available in a trusted form, when and where required, leads to quicker and more soundly based clinical decisions and hence improvements in effi ciency, safety and patient outcomes.

The Offi ce of the National Coordinator (ONC) for health information technology (HIT) has specifi ed the standards to be used for electronic data interchange, clinical documents, terminology, privacy, and information security, in order for healthcare providers to qualify for incentive payments of over $35 billion. However, many of these HIT standards are complex and the barriers to adoption are now being addressed. The standards development organizations have recognized the need to introduce education on HIT standards into the higher education curriculum of both clinicians and HIT professionals.

This series sets out to elucidate key HIT standards in a form that is accessible to both students and practitioners. The focus is on specifi c groups of standards and on how to use them individually and in combination. Usually, a single author who has been actively involved in the development, use, or teaching of these standards writes each book to provide a coherent viewpoint.

Tim Benson

xv

About the Author

Tim Benson graduated from the University of Nottingham as a mechanical engineer and was introduced to healthcare computing at the Charing Cross Hospital in London (now part of Imperial College Healthcare NHS Trust), where he evaluated the socioeconomic benefi ts of medical computing systems. In 1980, he founded Abies Informatics Ltd, one of the fi rst GP computer suppliers where, with James Read and David Markwell, they developed the Read codes, which evolved to become the national standard for UK primary care and one of the two sources of SNOMED CT. In 1990, he led the fi rst European project team to assess the need for open stan-dards in health informatics, which led to the European Committee for Health Informatics Standards (CEN TC251) and two decades of work on interoperability standards and collaboration with HL7.

For further information, see www.abies.co.uk .

xvii

Acknowledgments

I am grateful to the many people who made useful comments on the fi rst edition of this book. I want to thank in particular Dr. Mary Hawking to allow me to reproduce her story of Fred and his dog and to Dr. Malcolm Duncan for permission to repro-duce the story of the Chocolate Teapot.

Many people have contributed to my understanding of this healthcare interoper-ability HL7 and SNOMED. Dr. David Markwell, my friend and collaborator over 25 years, has made an outstanding personal contribution to both SNOMED CT and HL7. In the HL7 space, I want to thank and acknowledge my debt to Ed Hammond, Mark Schafarman, Jack Harrington, Clem McDonald, Woody Beeler, Charlie Mead, Bob Dolin, Mike Henderson, Abdul-Malik Shakir, Virginia Lorenzi and Rn Spronk, Charlie McCay, Leo Fogarty, Andrew Hinchley, Martin Whittaker, and Ann Wrightson. In clinical terminology, I have learned much from Alan Rector, Kent Spackman, Ed Cheetham, James Read, and Tom Marley. I would also like to thank Ed Conley, Pete Burnap, Roddy Neame, Justin Whatling, Sigurd From, Larry Weed, Georges de Moor, Seref Arikan, Michael Houghton, Timur Cevik, and David Ingram for their help in different ways.

Finally, I wish to acknowledge all the great people who have made HL7 and SNOMED what they are today.

This book includes copyright material on HL7 which is reproduced with the kind permission of HL7 International and on SNOMED CT, which is reproduced with the kind permission of the International Health Terminology Standards Development Organisation (IHTSDO); Health Level Seven and HL7 are registered trademarks of Health Level Seven International, Inc. IHTSDO , SNOMED , and SNOMED CT are registered trademarks of the International Health Terminology Standards Development Organisation.

xix

Contents

Part I Principles of Health Interoperability

1 The Health Information Revolution ...................................................... 3Healthcare is Communication ................................................................... 3Information Handling ................................................................................ 6

Use of Information ................................................................................. 6Clinical Decisions ..................................................................................... 7Lessons of History .................................................................................... 9

El Camino Hospital ................................................................................ 9Problem-Oriented Medical Records ...................................................... 10Success in GP Surgeries ........................................................................ 11Failure in NHS Hospitals ....................................................................... 11The NHS National Programme .............................................................. 12Canada ................................................................................................... 14Denmark ................................................................................................ 14

Meaningful Use ......................................................................................... 14References ................................................................................................. 19

2 Why Interoperability is Hard ................................................................ 21Why Standards are Needed ....................................................................... 22Electronic Health Records ........................................................................ 24The Devil is in the Detail .......................................................................... 26Complexity Creates Errors ........................................................................ 29References ................................................................................................. 31

3 Models ..................................................................................................... 33The Importance of Models ........................................................................ 33

Models in Interoperability Standards ..................................................... 34Model-driven Architecture..................................................................... 35

Life Cycle .................................................................................................. 36Scope ......................................................................................................... 36

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Storyboards ............................................................................................... 38Requirements Specifi cation ...................................................................... 41Conceptual Design .................................................................................... 42Technology-Specifi c Specifi cation ............................................................ 44An Example: Colorectal Cancer Referral ................................................. 45References ................................................................................................. 49

4 UML and XML ....................................................................................... 51UML .......................................................................................................... 51

Class Diagrams ...................................................................................... 53Modeling Behavior ................................................................................ 57

BPMN ....................................................................................................... 61XML .......................................................................................................... 64

XML Documents ................................................................................... 64XML Elements ....................................................................................... 65

XML Attributes ......................................................................................... 66XML Schema ......................................................................................... 66Namespaces ........................................................................................... 68Style Sheets ............................................................................................ 68XPath ..................................................................................................... 68

Reference .................................................................................................. 70

5 Privacy ..................................................................................................... 71Data Protection .......................................................................................... 72

OECD Principles ................................................................................... 73Information Governance ........................................................................ 74Authentication ........................................................................................ 75Authorization ......................................................................................... 75

Consent Management ................................................................................ 76Cryptography ............................................................................................ 78

Digital Signature .................................................................................... 80Encryption .............................................................................................. 80Other Security Services ......................................................................... 81

Refere nces ................................................................................................. 81

6 Standards Development Organizations ................................................ 83What is a Standard? .................................................................................. 83How Standards Bodies Work .................................................................... 85Standards Development Organizations (SDOs) ........................................ 86HL7 International ...................................................................................... 87

HL7 Products ......................................................................................... 89Ballot Process ........................................................................................ 89Membership ........................................................................................... 90The Technical Steering Committee........................................................ 92

IHTSDO .................................................................................................... 92IHE ........................................................................................................... 94

xxiContents

Continua Alliance ..................................................................................... 94CDISC ....................................................................................................... 95OpenEHR .................................................................................................. 96Open Health Tools .................................................................................... 97References ................................................................................................. 98

Part II HL7 and Interchange Formats

7 HL7 Version 2 .......................................................................................... 101Message Syntax ........................................................................................ 102

Delimiters .............................................................................................. 103Segment Defi nition ................................................................................ 106

Segments ................................................................................................... 107Message Heavder MSH ......................................................................... 107Event Type (EVN) ................................................................................. 109Patient Identifi cation Details (PID)........................................................ 109Patient Visit (PV1) ................................................................................. 110Request and Specimen Details (OBR) ................................................... 110Result Details (OBX) ............................................................................. 110Z-Segments ............................................................................................ 111

A Simple Example .................................................................................... 112Data Types................................................................................................. 113

Simple Data Types ................................................................................. 113Complex Data Types .............................................................................. 114Names and Addresses ............................................................................ 116Other Complex Data Types .................................................................... 116

HL7 V2 Tables .......................................................................................... 116HL7 V2 Documentation ............................................................................ 118Further Reading ........................................................................................ 119

8 The HL7 V3 RIM .................................................................................... 121Origins ....................................................................................................... 121Overview ................................................................................................... 122The RIM Backbone ................................................................................... 123

Common Attributes................................................................................ 125Act ........................................................................................................... 126Entity ......................................................................................................... 130Role ........................................................................................................... 133Association Classes ................................................................................... 133V3 Data Types ........................................................................................... 135

Basic Data Types ................................................................................... 135Instance Identifi er (II) ............................................................................ 135Code Data Types .................................................................................... 137Dates and Times ..................................................................................... 139Name and Address ................................................................................. 139Generic Collections ............................................................................... 140

xxii Contents

Special Fields ............................................................................................ 140Use of the RIM .......................................................................................... 140References ................................................................................................. 141

9 Constrained Information Models .......................................................... 143Types of Model ......................................................................................... 143Types of Constraint ................................................................................... 145Vocabulary and Value Sets ........................................................................ 146Artifact Names .......................................................................................... 146A Simple Example .................................................................................... 147RMIM Notation ........................................................................................ 149

Tooling ................................................................................................... 152Templates ............................................................................................... 152

Clinical Statement Pattern ......................................................................... 152Relationships between Entries ............................................................... 153

HL7 Development Framework.................................................................. 154Profi les ................................................................................................... 156Implementation Technology Specifi cation (ITS) ................................... 156

Documentation .......................................................................................... 157

10 Clinical Document Architecture ............................................................ 159The Document Paradigm .......................................................................... 159CDA History ............................................................................................. 161Header ....................................................................................................... 162

Patient .................................................................................................... 165Author .................................................................................................... 166Steward .................................................................................................. 167Other Participants .................................................................................. 167Relationships .......................................................................................... 167

Body .......................................................................................................... 169Section ................................................................................................... 169Clinical Statement .................................................................................. 171

CDA Templates ......................................................................................... 171Continuity of Care Document (CCD) ....................................................... 173

CCD Body ............................................................................................. 175greenCDA ................................................................................................. 176Reference .................................................................................................. 178

11 HL7 Dynamic Model............................................................................... 179Interaction ................................................................................................. 179Trigger Event ............................................................................................ 179Application Role ....................................................................................... 181Message Type ............................................................................................ 182Interaction Sequence ................................................................................. 182Message Wrapper ...................................................................................... 182

xxiiiContents

Query ......................................................................................................... 184Acknowledgement .................................................................................... 184Safety ........................................................................................................ 184

12 IHE XDS .................................................................................................. 187Why XDS? ................................................................................................ 187XDS Metadata ........................................................................................... 188

Document Data ...................................................................................... 189Patient Data ............................................................................................ 190Author Data ........................................................................................... 191Event Data.............................................................................................. 192Technical Data ....................................................................................... 192Submission Sets and Folders ................................................................. 193

XDS Transactions and Extensions ............................................................ 193Point-to-Point Transmission .................................................................. 195Information Retrieval ............................................................................. 196Security Profi les ..................................................................................... 196OpenExchange ....................................................................................... 197

References ................................................................................................. 198

Part III SNOMED and Terminology

13 Clinical Terminology ............................................................................... 201Importance ................................................................................................ 201Coding and Classifi cation ......................................................................... 203Terminology Terms ................................................................................... 205User Requirements .................................................................................... 206Ciminos Desiderata .................................................................................. 208References ................................................................................................. 213

14 Coding and Classifi cation Schemes ....................................................... 215International Classifi cation of Diseases .................................................... 215Diagnosis-Related Groups ........................................................................ 217The Read Codes ........................................................................................ 218

Hierarchical Codes ................................................................................. 219Automatic Encoding .............................................................................. 220Diseases ................................................................................................. 221Procedures .............................................................................................. 221History/Symptoms ................................................................................. 222Occupations ........................................................................................... 223Examination/Signs ................................................................................. 223Prevention .............................................................................................. 224Administration ....................................................................................... 225Drugs ...................................................................................................... 225Development .......................................................................................... 225

xxiv Contents

Why Read Codes Were Successful ........................................................ 226Problems ................................................................................................ 227

SNOP and SNOMED ................................................................................ 228LOINC ...................................................................................................... 229UMLS ....................................................................................................... 231References ................................................................................................. 232

15 SNOMED CT .......................................................................................... 233Introduction ............................................................................................... 233Components .............................................................................................. 235

The SctId ................................................................................................ 235Concept .................................................................................................. 237Description ............................................................................................. 238Relationships .......................................................................................... 239

Expressions ............................................................................................... 240Precoordination ...................................................................................... 243Postcoordination .................................................................................... 243Axis Modifi cation .................................................................................. 243Subsumption Testing.............................................................................. 245

Other Aspects ............................................................................................ 245Subsets ................................................................................................... 245Cross Mappings ..................................................................................... 247History Files ........................................................................................... 248Releases ................................................................................................. 248Documentation ....................................................................................... 250

References ................................................................................................. 250

16 SNOMED CT Concept Model ............................................................... 253SNOMED Hierarchies .............................................................................. 253Attributes ................................................................................................... 254Object Hierarchies .................................................................................... 256

Clinical Findings .................................................................................... 256Procedures .............................................................................................. 258Situations with Explicit Context ............................................................ 261Observable Entities ................................................................................ 261Event ...................................................................................................... 262

Value Hierarchies ...................................................................................... 262Body Structure ....................................................................................... 262Organism ................................................................................................ 263Substance ............................................................................................... 263Pharmaceutical/Biologic Product .......................................................... 263Physical Object ...................................................................................... 263Physical Force ........................................................................................ 264Social Context ........................................................................................ 264Environments and Geographic Locations .............................................. 264

xxvContents

Miscellaneous Hierarchies ........................................................................ 264Qualifi er Value ....................................................................................... 264Special Concept ..................................................................................... 264Record Artifact ...................................................................................... 264Core Metadata Concept ......................................................................... 265Foundation Metadata Concept ............................................................... 265Linkage Concept .................................................................................... 265

17 Using SNOMED and HL7 Together ...................................................... 267Terminology Binding ................................................................................ 267Model of Use ............................................................................................. 268Model of Meaning ..................................................................................... 272Structural Models ...................................................................................... 273Implementation Issues .............................................................................. 275When to Use HL7 and SNOMED ............................................................. 277References ................................................................................................. 279

Glossary ........................................................................................................... 281

Further Reading .............................................................................................. 301

Index ................................................................................................................ 309

Principles of Health Interoperability HL7 and SNOMEDCopyright PageDedicationForeword to the First EditionForeword to the Second EditionPrefaceSeries PrefaceAbout the AuthorAcknowledgmentsContents