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Pro's and con's of the stepped wedge design in cluster randomised trials of quality improvement interventions: two current examples.

Dreischulte, Tobias; Grant, Aileen; Donnan, Peter; Guthrie, Bruce

Authors

Tobias Dreischulte

Peter Donnan

Bruce Guthrie



Abstract

The stepped wedge design, under which all trial participants receive the intervention but the order in which the intervention is received is randomised, is potentially useful to rigorously evaluate organisational interventions to improve quality and safety. We use two examples of cluster-randomised stepped-wedge trials (DQIP and GP-POLY) to illustrate advantages and disadvantages of the design in evaluations of complex prescribing improvement interventions in primary care. DQIP is nearing completion and GP-POLY will start in 2013. The intervention in both DQIP and GP-Poly involves outreach visits by researchers for education and informatics tool training, making sequential roll out a logistic necessity. The stepped wedge allows for this by design, but trial durations may be prolonged compared to parallel-arm trials and other designs, and arranging initiation visits to fit with randomisation schedules is challenging. Since all participants receive the intervention and there are multiple repeated measurements, practice sample size requirements in DQIP and GP-POLY were reduced compared to a parallel-arm design, but power calculations are more complex. Recruitment may be improved by offering the intervention to all participants, but creates potential problems for retention and avoiding contamination in practices with long lags between recruitment and intervention start. Because of the vulnerability of stepped wedge trials to time varying confounding, avoiding changes in intervention delivery to successive cohorts is important and needs careful planning. The stepped wedge design is attractive for cluster randomised trials of quality improvement interventions, especially when staggering of intervention delivery is inevitable, but presents challenges for implementation that need careful planning. Oral presentation presented at the 2nd Clinical Trials Methodology Conference 2013: Methodology matters, 18-19 November 2013, Edinburgh, UK.

Citation

DREISCHULTE, T., GRANT, A., DONNAN, P. and GUTHRIE, B. 2013. Pro's and con's of the stepped wedge design in cluster randomised trials of quality improvement interventions: two current examples. Trials [online], 14(Supplement 1): oral and poster presentations of the 2nd Clinical trials methodology conference 2013: methodology matters, 18-19 November 2013, Edinburgh, UK, abstract O87. Available from: https://doi.org/10.1186/1745-6215-14-S1-O87

Journal Article Type Meeting Abstract
Conference Name 2nd Clinical trials methodology conference 2013: methodology matters
Conference Location Edinburgh, UK
Acceptance Date Nov 29, 2013
Online Publication Date Nov 29, 2013
Publication Date Nov 29, 2013
Publicly Available Date Jun 18, 2019
Journal Trials
Print ISSN 1745-6215
Electronic ISSN 1745-6215
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 14
Issue Supplement 1
Article Number O87
DOI https://doi.org/10.1186/1745-6215-14-S1-O87
Keywords Careful planning; Intervention delivery; Sample size; Requirement; Trial duration; Organisational intervention
Public URL https://rgu-repository.worktribe.com/output/248993

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