OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come Cochrane Handbook for Systematic Reviews of Interventions Cochrane Book Series Edited by Julian PT Higgins and Sally Green THE COCHRANE A John Wiley & Sons, Ltd., Publication COLLABORATION® OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come Cochrane Handbook for Systematic Reviews of Interventions OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come Cochrane Handbook for Systematic Reviews of Interventions Cochrane Book Series Edited by Julian PT Higgins and Sally Green THE COCHRANE A John Wiley & Sons, Ltd., Publication COLLABORATION® OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come Copyright C 2008 The Cochrane Collaboration This work is a co-publication between The Cochrane Collaboration and John Wiley & Sons Ltd. 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Some content that appears in print may not be available in electronic books. Library of Congress Cataloging-in-Publication Data Cochrane handbook for systematic reviews of interventions / edited by Julian Higgins and Sally Green. p. ; cm.—(Cochrane book series) Includes bibliographical references and index. ISBN 978-0-470-69951-5 (alk. paper)—ISBN 978-0-470-05796-4 (alk. paper) 1. Evidence-based medicine—Methodology. 2. Medicine—Research—Evaluation. 3. Outcome assessment (Medical care) 4. Meta-analysis. I. Higgins, Julian. II. Green, Sally, Prof. III. Cochrane Collaboration. IV. Series. [DNLM: 1. Outcome and Process Assessment (Health Care) 2. Evidence-Based Medicine—methods. 3. Meta-Analysis as Topic. 4. Review Literature as Topic. WA 84.1 C663 2008] R723.7.C63 2008 610.72—dc22 2008022132 British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 978-0-470-51845-8 Typeset in 10.5/12.5pt Times by Aptara Inc., New Delhi, India Printed and bound in Great Britain by Antony Rowe Ltd, Chippenham, Wiltshire This book is printed on acid-free paper responsibly manufactured from sustainable forestry in which at least two trees are planted for each one used for paper production. OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come Contents Preface xiii Acknowledgements xv The Handbook editors xvii Major contributors xix Part 1 COCHRANE REVIEWS 1 1 Introduction 3 Sally Green, Julian PT Higgins, Philip Alderson, Mike Clarke, Cynthia D Mulrow and Andrew D Oxman 1.1 The Cochrane Collaboration 3 1.2 Systematic reviews 6 1.3 About this Handbook 7 1.4 Contributors to the Handbook 8 1.5 Chapter information 9 1.6 References 9 2 Preparing a Cochrane review 11 Edited by Sally Green and Julian PT Higgins 2.1 Rationale for protocols 11 2.2 Format of a Cochrane review 12 2.3 Logistics of doing a review 13 2.4 Publication of Cochrane reviews in print journals and books 24 2.5 Publication of previously published reviews as Cochrane reviews 26 2.6 Declaration of interest and commercial sponsorship 26 2.7 Chapter information 29 2.8 References 29 3 Maintaining reviews: updates, amendments and feedback 31 Julian PT Higgins, Sally Green and Rob JPM Scholten 3.1 Introduction 31 3.2 Some important definitions 32 OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come vi CONTENTS 3.3 Important dates associated with Cochrane reviews 39 3.4 Considerations when updating a Cochrane review 42 3.5 ‘What’s new’ and History tables 46 3.6 Incorporating and addressing feedback in a Cochrane review 48 3.7 Chapter information 48 3.8 References 49 4 Guide to the contents of a Cochrane protocol and review 51 Edited by Julian PT Higgins and Sally Green 4.1 Introduction 52 4.2 Title and review information (or protocol information) 52 4.3 Abstract 55 4.4 Plain language summary 55 4.5 Main text 55 4.6 Tables 70 4.7 Studies and references 72 4.8 Data and analyses 74 4.9 Figures 76 4.10 Sources of support to the review 77 4.11 Feedback 77 4.12 Appendices 78 4.13 Chapter information 78 4.14 References 78 Part 2 GENERAL METHODS FOR COCHRANE REVIEWS 81 5 Defining the review question and developing criteria for including studies 83 Edited by Denise O’Connor, Sally Green and Julian PT Higgins 5.1 Questions and eligibility criteria 84 5.2 Defining types of participants: which people and populations? 85 5.3 Defining types of interventions: which comparisons to make? 86 5.4 Defining types of outcomes: which outcome measures are most important? 87 5.5 Defining types of study 90 5.6 Defining the scope of a review question (broad versus narrow) 91 5.7 Changing review questions 93 5.8 Chapter information 93 5.9 References 94 6 Searching for studies 95 Carol Lefebvre, Eric Manheimer and Julie Glanville on behalf of the Cochrane Information Retrieval Methods Group 6.1 Introduction 96 6.2 Sources to search 98 6.3 Planning the search process 118 6.4 Designing search strategies 128 6.5 Managing references 142 OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come CONTENTS vii 6.6 Documenting and reporting the search process 144 6.7 Chapter information 146 6.8 References 147 7 Selecting studies and collecting data 151 Edited by Julian PT Higgins and Jonathan J Deeks 7.1 Introduction 151 7.2 Selecting studies 152 7.3 What data to collect 156 7.4 Sources of data 163 7.5 Data collection forms 164 7.6 Extracting data from reports 167 7.7 Extracting study results and converting to the desired format 170 7.8 Managing data 182 7.9 Chapter information 183 7.10 References 183 8 Assessing risk of bias in included studies 187 Edited by Julian PT Higgins and Douglas G Altman on behalf of the Cochrane Statistical Methods Group and the Cochrane Bias Methods Group 8.1 Introduction 188 8.2 What is bias? 188 8.3 Tools for assessing quality and risk of bias 190 8.4 Introduction to sources of bias in clinical trials 193 8.5 The Cochrane Collaboration’s tool for assessing risk of bias 194 8.6 Presentation of assessments of risk of bias 202 8.7 Summary assessments of risk of bias 202 8.8 Incorporating assessments into analyses 206 8.9 Sequence generation 210 8.10 Allocation sequence concealment 214 8.11 Blinding of participants, personnel and outcome assessors 217 8.12 Incomplete outcome data 219 8.13 Selective outcome reporting 226 8.14 Other potential threats to validity 230 8.15 Chapter information 234 8.16 References 235 9 Analysing data and undertaking meta-analyses 243 Edited by Jonathan J Deeks, Julian PT Higgins and Douglas G Altman on behalf of the Cochrane Statistical Methods Group 9.1 Introduction 244 9.2 Types of data and effect measures 249 9.3 Study designs and identifying the unit of analysis 260 9.4 Summarizing effects across studies 263 9.5 Heterogeneity 276 9.6 Investigating heterogeneity 282 9.7 Sensitivity analyses 289 9.8 Chapter information 292 9.9 References 293 OTE/SPH OTE/SPH JWBK247-FM August 22, 2008 20:58 Printer Name: Yet to Come viii CONTENTS 10 Addressing reporting biases 297 Edited by Jonathan AC Sterne, Matthias Egger and David Moher on behalf of the Cochrane Bias Methods Group 10.1 Introduction 298 10.2 Types of reporting biases and the supporting evidence 299 10.3 Avoiding reporting biases 308 10.4 Detecting reporting biases 310 10.5 Chapter information 324 10.6 References 325 11 Presenting results and ‘Summary of findings’ tables 335 Holger J Schunemann,¨ Andrew D Oxman, Julian PT Higgins, Gunn E Vist, Paul Glasziou and Gordon H Guyatt on behalf of the Cochrane Applicability and Recommendations Methods Group and the Cochrane Statistical Methods Group