Projects per year
Abstract
It is a pragmatic study design which can reconcile the need for robust evaluations with political or logistical constraints. While not exclusively for the evaluation of service delivery interventions, it is particularly suited to evaluations that do not rely on individual patient recruitment. As in all cluster trials, stepped wedge trials with individual recruitment and without concealment of allocation (or blinding of the intervention) are at risk of selection biases.
In a stepped wedge design more clusters are exposed to the intervention towards the end of the study than in its early stages. This implies that the effect of the intervention might be confounded with any underlying temporal trend. A result that initially might seem suggestive of an effect of the intervention may therefore transpire to be the result of a positive underlying temporal trend. Sample size calculations and analysis must make allowance for both the clustered nature of the design and the confounding effect of time.
The stepped wedge cluster randomised trial is an alternative to traditional parallel cluster studies, in which the intervention is delivered in only half the clusters with the remainder functioning as controls. When the clusters are relatively homogeneous (that is, the intra-cluster correlation is small), parallel studies tend to deliver better statistical performance than a stepped wedge trial. However, if substantial cluster-level effects are present (that is, larger intra-cluster correlations) or the clusters are large, the stepped wedge design will be more powerful than a parallel design, even one in which the intervention is preceded by a period of baseline control observations.
Original language | English |
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Article number | h391 |
Journal | BMJ |
Volume | 350 |
DOIs | |
Publication status | Published - 6 Feb 2015 |
Keywords
- Clinical Protocols
- Cluster Analysis
- Data Interpretation, Statistical
- Humans
- Randomized Controlled Trials as Topic
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Dive into the research topics of 'The stepped wedge cluster randomised trial : rationale, design, analysis, and reporting'. Together they form a unique fingerprint.Projects
- 3 Finished
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Linked to RRAK13548: Midland Hub for Trials Methodology Research
Billingham, L. (Principal Investigator)
1/04/11 → 31/03/14
Project: Research Councils
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Linked to a/c DJAB RRAK13548 - Midland Hub for Trials Methodology Research at University of Birmingham
Billingham, L. (Principal Investigator), Bryan, S. (Co-Investigator), Calvert, M. (Co-Investigator), Deeks, J. (Co-Investigator), Delaney, B. (Co-Investigator), Freemantle, N. (Co-Investigator), Gray, R. (Co-Investigator), Hobbs, R. (Co-Investigator), Johnson, P. (Co-Investigator), Lilford, R. (Co-Investigator), Wheatley, K. (Co-Investigator) & Zeegers, M. (Co-Investigator)
1/06/09 → 31/05/14
Project: Research Councils
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Linked to a/c DMAB.RRAK14731 Midland Hub for Trials Methodology Research at University of Birmingham
Billingham, L. (Principal Investigator), Bryan, S. (Co-Investigator), Calvert, M. (Co-Investigator), Deeks, J. (Co-Investigator), Delaney, B. (Co-Investigator), Freemantle, N. (Co-Investigator), Gray, R. (Co-Investigator), Hobbs, R. (Co-Investigator), Johnson, P. (Co-Investigator), Lilford, R. (Co-Investigator), Wheatley, K. (Co-Investigator), Zeegers, M. (Co-Investigator) & Wilson, S. (Co-Investigator)
1/06/09 → 31/05/14
Project: Research Councils