ebook img

Cluster Randomised Trials PDF

326 Pages·2009·3.06 MB·English
Save to my drive
Quick download
Download
Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.

Preview Cluster Randomised Trials

CLUSTER RANDOMISED TRIALS CC88116644__CC000000..iinndddd ii 1111//1177//0088 1100::0044::0033 AAMM CHAPMAN & HALL/CRC Interdisciplinar y Statistics Series Series editors: N. Keiding, B.J.T. Morgan, C.K. Wikle, P. van der Heijden Published titles AN INVARIANT APPROACH TO S. Lele and J. Richtsmeier STATISTICAL ANALYSIS OF SHAPES ASTROSTATISTICS G. Babu and E. Feigelson BAYESIAN DISEASE MAPPING: Andrew B. Lawson HIERARCHICAL MODELING IN SPATIAL EPIDEMIOLOGY BIOEQUIVALENCE AND S. Patterson and STATISTICS IN CLINICAL B. Jones PHARMACOLOGY CLINICAL TRIALS IN ONCOLOGY J. Crowley, S. Green, SECOND EDITION and J. Benedetti CLUSTER RANDOMISED TRIALS R.J. Hayes and L.H. Moulton CORRESPONDENCE ANALYSIS M. Greenacre IN PRACTICE, SECOND EDITION DESIGN AND ANALYSIS OF D.L. Fairclough QUALITY OF LIFE STUDIES IN CLINICAL TRIALS DYNAMICAL SEARCH L. Pronzato, H. Wynn, and A. Zhigljavsky GENERALIZED LATENT VARIABLE A. Skrondal and MODELING: MULTILEVEL, S. Rabe-Hesketh LONGITUDINAL, AND STRUCTURAL EQUATION MODELS GRAPHICAL ANALYSIS OF K. Basford and J. Tukey MULTI-RESPONSE DATA INTRODUCTION TO M. Waterman COMPUTATIONAL BIOLOGY: MAPS, SEQUENCES, AND GENOMES MARKOV CHAIN MONTE CARLO W. Gilks, S. Richardson, IN PRACTICE and D. Spiegelhalter CC88116644__CC000000..iinndddd iiii 1111//1177//0088 1100::0044::0044 AAMM Published titles MEASUREMENT ERROR AND P. Gustafson MISCLASSIFICATION IN STATISTICS AND EPIDEMIOLOGY: IMPACTS AND BAYESIAN ADJUSTMENTS META-ANALYSIS OF BINARY DATA D. Böhning, R. Kuhnert, USING PROFILE LIKELIHOOD and S. Rattanasiri STATISTICAL ANALYSIS OF GENE T. Speed EXPRESSION MICROARRAY DATA STATISTICAL AND COMPUTATIONAL R. Wu and M. Lin PHARMACOGENOMICS STATISTICS IN MUSICOLOGY J. Beran STATISTICAL CONCEPTS J. Aitchison, J.W. Kay, AND APPLICATIONS IN and I.J. Lauder CLINICAL MEDICINE STATISTICAL AND PROBABILISTIC P.J. Boland METHODS IN ACTUARIAL SCIENCE STATISTICAL DETECTION AND P. Rogerson and I. Yamada SURVEILLANCE OF GEOGRAPHIC CLUSTERS STATISTICS FOR ENVIRONMENTAL A. Bailer and W. Piegorsch BIOLOGY AND TOXICOLOGY STATISTICS FOR FISSION R.F. Galbraith TRACK ANALYSIS CC88116644__CC000000..iinndddd iiiiii 1111//1177//0088 1100::0044::0044 AAMM Chapman & Hall/CRC Interdisciplinary Statistics Series CLUSTER RANDOMISED TRIALS Richard J. Hayes Lawrence H. Moulton CC88116644__CC000000..iinndddd vv 1111//1177//0088 1100::0044::0055 AAMM Chapman & Hall/CRC Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 Chapman & Hall/CRC is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-13: 978-1-58488-816-1 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, trans- mitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Hayes, Richard J., DSc. Cluster randomised trials / authors, Richard J. Hayes and Lawrence H. Moulton. p. ; cm. -- (Interdisciplinary statistics) “A CRC title.” Includes bibliographical references and index. ISBN 978-1-58488-816-1 (hardcover : alk. paper) 1. Clinical trials. 2. Cluster analysis. I. Moulton, Lawrence H. II. Title. III. Series. [DNLM: 1. Cluster Analysis. 2. Randomized Controlled Trials as Topic--methods. 3. Data Interpretation, Statistical. WA 950 H418c 2009] R853.C55H39 2009 615.5072’4--dc22 2008035804 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com CC88116644__CC000000..iinndddd vvii 1111//1177//0088 1100::0044::0055 AAMM To our families: Anne, Clare and Emma; Ann, Carine and Tyler. CC88116644__CC000000dd..iinndddd vviiii 1111//1177//0088 99::5599::2266 AAMM Contents Preface ......................................................................................................xvii Authors .......................................................................................................xix Glossary of Notation .................................................................................xxi Part A: Basic Concepts 1 Introduction ........................................................................................3 1.1 Randomised Trials................................................................................3 1.1.1 Randomising Clusters ..............................................................4 1.1.2 Some Case Studies ....................................................................6 1.1.3 Overview of Book .....................................................................8 2 Variability between Clusters ..........................................................11 2.1 Introduction .........................................................................................11 2.2 The Implications of Between-cluster Variability: Some Examples ....................................................................................12 2.3 Measures of Between-cluster Variability ........................................15 2.3.1 Introduction .............................................................................15 2.3.1.1 Binary Outcomes and Proportions .........................15 2.3.1.2 Event Data and Person-years Rates .........................15 2.3.1.3 Quantitative Outcomes and Means ........................16 2.3.2 Coeffi cient of Variation, k .......................................................16 2.3.3 Intracluster Correlation Coeffi cient, ρ ..................................17 2.3.3.1 Quantitative Outcomes .............................................17 2.3.3.2 Binary Outcomes .......................................................18 2.3.3.3 Estimation of ρ ...........................................................18 2.3.4 Relationship between k and ρ ...............................................18 2.4 The Design Effect ................................................................................19 2.4.1 Binary Outcomes .....................................................................19 2.4.2 Quantitative Outcomes ..........................................................21 2.5 Sources of Within-cluster Correlation .............................................22 2.5.1 Clustering of Population Characteristics .............................22 2.5.2 Variations in Response to Intervention ...............................22 2.5.3 Correlation Due to Interaction between Individuals .........23 3 Choosing Whether to Randomise by Cluster ...............................25 3.1 Introduction .........................................................................................25 3.2 Rationale for Cluster Randomisation ..............................................25 3.2.1 Type of Intervention ...............................................................25 ix CC88116644__CC000000ttoocc..iinndddd iixx 1122//33//0088 11::0000::4466 PPMM x Contents 3.2.2 Logistical Convenience and Acceptability ..........................26 3.2.3 Contamination .........................................................................27 3.3 Using Cluster Randomisation to Capture Indirect Effects of Intervention ........................................................................28 3.3.1 Introduction .............................................................................28 3.3.2 Effects of an Intervention on Infectiousness .......................29 3.3.3 Mass Effects of Intervention ..................................................31 3.3.4 Direct, Indirect, Total and Overall Effects ...........................33 3.4 Disadvantages and Limitations of Cluster Randomisation ....................................................................................37 3.4.1 Effi ciency ..................................................................................37 3.4.2 Selection Bias ...........................................................................37 3.4.3 Imbalances between Study Arms .........................................39 3.4.4 Generalisability .......................................................................40 Part B: Design Issues 4 Choice of Clusters ............................................................................45 4.1 Introduction .........................................................................................45 4.2 Types of Cluster ..................................................................................45 4.2.1 Geographical Clusters ............................................................45 4.2.1.1 Communities ..............................................................46 4.2.1.2 Administrative Units ................................................47 4.2.1.3 Arbitrary Geographical Zones ................................48 4.2.2 Institutional Clusters ..............................................................49 4.2.2.1 Schools ........................................................................49 4.2.2.2 Health Units ...............................................................50 4.2.2.3 Workplaces .................................................................50 4.2.3 Smaller Clusters ......................................................................51 4.2.3.1 Households and Other Small Groups ....................52 4.2.3.2 Individuals as Clusters .............................................52 4.3 Size of Clusters ....................................................................................53 4.3.1 Introduction .............................................................................53 4.3.2 Statistical Considerations .......................................................53 4.3.3 Logistical Issues ......................................................................54 4.3.4 Contamination .........................................................................55 4.3.4.1 Contacts between Intervention and Control Clusters .........................................................55 4.3.4.2 Contacts between Intervention Clusters and the Wider Population ................................................55 4.3.4.3 Contacts between Control Clusters and the Wider Population ........................................56 4.3.4.4 Effects of Cluster Size on Contamination ..............56 4.3.5 Transmission Zones of Infectious Diseases ........................56 CC88116644__CC000000ttoocc..iinndddd xx 1122//33//0088 11::0000::4477 PPMM Contents xi 4.4 Strategies to Reduce Contamination ................................................58 4.4.1 Separation of Clusters.............................................................58 4.4.2 Buffer Zones .............................................................................60 4.4.3 The Fried Egg Design .............................................................62 4.5 Levels of Randomisation, Intervention, Data Collection and Inference .......................................................................................64 5 Matching and Stratification ............................................................65 5.1 Introduction .........................................................................................65 5.2 Rationale for Matching ......................................................................65 5.2.1 Avoiding Imbalance between Treatment Arms .................66 5.2.2 Improving Study Power and Precision ................................68 5.3 Disadvantages of Matching ...............................................................70 5.3.1 Loss of Degrees of Freedom ..................................................70 5.3.2 Drop-out of Clusters ...............................................................72 5.3.3 Limitations in Statistical Inference for Matched Trials .....74 5.3.3.1 Adjustment for Covariates .......................................74 5.3.3.2 Testing for Variation in Intervention Effect ...........74 5.3.3.3 Estimation of Intracluster Correlation Coeffi cient and Coeffi cient of Variation .................75 5.4 Stratifi cation as an Alternative to Matching ...................................75 5.5 Choice of Matching Variables ...........................................................77 5.5.1 Estimating the Matching Correlation ..................................77 5.5.2 Matching on Baseline Values of Endpoint of Interest........78 5.5.3 Matching on Surrogate Variables .........................................79 5.5.4 Matching on Multiple Variables ............................................79 5.5.5 Matching on Location .............................................................80 5.6 Choosing Whether to Match or Stratify ..........................................81 5.6.1 Introduction .............................................................................81 5.6.2 Trials with a Small Number of Clusters ..............................81 5.6.3 Trials with a Larger Number of Clusters.............................83 6 Randomisation Procedures .............................................................85 6.1 Introduction .........................................................................................85 6.2 Restricted Randomisation .................................................................86 6.2.1 Basic Principles ........................................................................86 6.2.2 Using Restricted Randomisation to Achieve Overall Balance ......................................................................................87 6.2.3 Balance Criteria .......................................................................89 6.2.4 Validity of Restricted Randomisation ..................................94 6.2.5 Restricted Randomisation with More than Two Treatment Arms ......................................................................99 6.3 Some Practical Aspects of Randomisation .....................................99 6.3.1 Concealment of Allocation ....................................................99 6.3.2 Public Randomisation ............................................................99 CC88116644__CC000000ttoocc..iinndddd xxii 1122//33//0088 11::0000::4477 PPMM xii Contents 7 Sample Size .....................................................................................105 7.1 Introduction .......................................................................................105 7.2 Sample Size for Unmatched Trials .................................................106 7.2.1 Event Rates .............................................................................107 7.2.2 Proportions ............................................................................109 7.2.3 Means ......................................................................................110 7.2.4 Variable Sample Size per Cluster ........................................111 7.2.5 Sample Size Calculations Based on Intracluster Correlation Coeffi cient .........................................................111 7.3 Sample Size for Matched and Stratifi ed Trials .............................113 7.3.1 Matched Trials .......................................................................113 7.3.1.1 Event Rates ...............................................................114 7.3.1.2 Proportions ...............................................................114 7.3.1.3 Means ........................................................................114 7.3.2 Stratifi ed Trials ......................................................................116 7.4 Estimating the Between-cluster Coeffi cient of Variation ........................................................................................117 7.4.1 Unmatched Trials ..................................................................117 7.4.1.1 Event Rates ...............................................................118 7.4.1.2 Proportions ...............................................................119 7.4.1.3 Means ........................................................................120 7.4.2 Matched and Stratifi ed Trials ..............................................120 7.4.2.1 Event Rates ...............................................................120 7.4.2.2 Proportions and Means ..........................................121 7.5 Choice of Sample Size in each Cluster ...........................................121 7.6 Further Issues in Sample Size Calculation....................................124 7.6.1 Trials with More than Two Treatment Arms ....................124 7.6.2 Trials with Treatment Arms of Unequal Size ...................124 7.6.3 Equivalence Trials .................................................................125 7.6.4 Power and Precision .............................................................126 7.6.5 Assumptions about Intervention Effects ...........................127 8 Alternative Study Designs ............................................................129 8.1 Introduction .......................................................................................129 8.2 Design Choices for Treatment Arms..............................................129 8.2.1 Trials with Several Treatment Arms ..................................129 8.2.2 Factorial Trials .......................................................................130 8.2.2.1 Independent Effects ................................................130 8.2.2.2 Non-independent Effects........................................132 8.2.3 Crossover Design ..................................................................135 8.2.4 Stepped Wedge Design ........................................................136 8.3 Design Choices for Impact Evaluation ..........................................141 8.3.1 Introduction ...........................................................................141 8.3.2 Repeated Cross-sectional Samples .....................................142 8.3.3 Cohort Follow-up ..................................................................143 CC88116644__CC000000ttoocc..iinndddd xxiiii 1122//33//0088 11::0000::4477 PPMM

See more

The list of books you might like

Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.