A Practical Guide to Cluster Randomised Trials in Health Services Research

by Eldridge, Sandra; Kerry, Sally

• ISBN13: 9780470510476
• ISBN10: 0470510471
• Edition: 1st
• Format: Hardcover
• Copyright: 2012-02-20
• Publisher: Wiley

Summary

There is relatively little literature on cluster randomized trials, with only two previous books on the subject, both now quite old, and neither were focused on the practical aspects of the trials. This book provides that much needed practical guide to the design, execution and analysis of cluster randomized trials in health services research. It also provides an overview of the topic's numerous recent developments since the 2000 publication of the last book in this area. The opening chapter defines and introduces cluster randomized trials, before going on to present an overview of the subject's history and recent developments. The following chapters focus on all the major issues presented in the order in which investigators think about issues when they are designing a trial. The chapters focus on: trial quality, reporting, how to design an intervention, how to ensure the validity of results, how to choose both the design and the analysis of the trial, sample size calculations, choosing an intra-cluster correlation coefficient, the uses of piloting, how to conduct a cost-effectiveness analysis, and how these trials should be synthesized. The book alsos contain numerous tables, graphs and diagrams and a substantial number examples of recent trials.

Author Biography

Sandra Eldridge – Senior Lecturer, Medical Statistics, Queen Mary, University of London, UK
Dr Eldridge is well experienced in designing and analyzing high quality cluster randomized trials, having worked on ten such trials since the mid 1990s. An award-winning speaker on randomized trials, Dr Eldridge has given numerous presentations in many settings and conferences over the last seven years.

Table of Contents

Preface	p. xiii
Notation	p. xv
Table of cases: Trials used as examples in more than one chapter in the book	p. xviii
Introduction	p. 1
Introduction to randomised trials	p. 2
Explanatory or pragmatic trials	p. 2
How does a cluster randomised trial differ from other trials?	p. 3
Between-cluster variability	p. 9
Why carry out cluster randomised trials?	p. 10
Quality of evidence from cluster randomised trials	p. 13
Historical perspectives	p. 16
Summary	p. 18
References	p. 19
Recruitment and ethics	p. 22
Selecting clusters and participants to enhance external validity	p. 22
Ethics of cluster randomised trials	p. 24
Selection and recruitment of participants to enhance internal validity	p. 35
Retention of participants in the trial	p. 41
Summary	p. 41
References	p. 41
Designing interventions	p. 44
Lack of effectiveness of interventions evaluated in cluster randomised trials	p. 45
What is a complex intervention?	p. 46
Phases in the development of a complex intervention	p. 50
Identifying evidence for potential intervention effect (pre-clinical phase)	p. 50
Understanding more about intervention components (modelling phase)	p. 53
Developing the optimum intervention and study design (exploratory trial phase)	p. 55
What is the intervention?	p. 57
Summary	p. 58
References	p. 58
Pilot and feasibility studies	p. 60
What is a pilot study?	p. 60
Reasons for conducting pilot and feasibility studies	p. 63
Designing a pilot or feasibility study	p. 69
Reporting and interpreting pilot studies	p. 71
Summary	p. 72
References	p. 73
Design	p. 74
Parallel designs with only two arms	p. 75
Cohort versus cross-sectional designs	p. 85
Parallel designs with more than two arms	p. 88
Crossover designs	p. 92
Further design considerations	p. 95
Summary	p. 96
References	p. 96
Analysis	p. 99
Data collection and management	p. 99
Analysis - an Introduction	p. 101
Analyses for two-arm, completely randomised, stratified or minimised designs	p. 104
Analyses for other designs	p. 124
Intention to treat and missing values	p. 129
Analysis planning	p. 131
Summary	p. 132
References	p. 133
Sample size calculations	p. 137
Factors affecting sample size for cluster randomised designs	p. 138
Calculating sample size using the intra-cluster correlation coeffi cient	p. 142
Sample size calculations for rates	p. 145
Restricted number of clusters	p. 146
Trials with a small number of clusters	p. 149
Variability in cluster size	p. 150
Comparison of different measures of between-cluster variability	p. 154
Matched and stratifi ed designs	p. 160
Sample size for other designs	p. 166
Summary	p. 169
References	p. 169
The intra-cluster correlation coeffi cient	p. 172
What is the ICC?	p. 173
Sources of ICC estimates	p. 175
Choosing the ICC for use in sample size calculations	p. 179
Calculating ICC values	p. 185
Uncertainty in ICCs	p. 192
Summary	p. 193
References	p. 193
Other topics	p. 196
Systematic reviews	p. 197
Cost effectiveness analyses	p. 207
Process evaluation	p. 212
Monitoring	p. 213
Summary	p. 215
References	p. 215
Trial reporting	p. 218
Trial quality and reporting quality	p. 218
Steps to improve trial reporting in the early stages of the trial	p. 227
Reporting randomised trials in journal and conference abstracts	p. 230
Application of CONSORT statement to cluster randomised trials	p. 232
Summary	p. 262
References	p. 263
Index	p. 267
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