The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures

Abstract Background We consider the design of stepped wedge trials with continuous recruitment and continuous outcome measures. Suppose we recruit from a fixed number of clusters where eligible participants present continuously, and suppose we have fine control over when each cluster crosses to the...

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Main Authors: Richard Hooper, Jessica Kasza, Andrew Forbes
Format: Article
Language:English
Published: BMC 2020-11-01
Series:BMC Medical Research Methodology
Subjects:
Online Access:http://link.springer.com/article/10.1186/s12874-020-01155-z
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author Richard Hooper
Jessica Kasza
Andrew Forbes
author_facet Richard Hooper
Jessica Kasza
Andrew Forbes
author_sort Richard Hooper
collection DOAJ
description Abstract Background We consider the design of stepped wedge trials with continuous recruitment and continuous outcome measures. Suppose we recruit from a fixed number of clusters where eligible participants present continuously, and suppose we have fine control over when each cluster crosses to the intervention. Suppose also that we want to minimise the number of participants, leading us to consider “incomplete” designs (i.e. without full recruitment). How can we schedule recruitment and cross-over at different clusters to recruit efficiently while achieving good precision? Methods The large number of possible designs can make exhaustive searches impractical. Instead we consider an algorithm using iterative improvements to hunt for an efficient design. At each iteration (starting from a complete design) a single participant – the one with the smallest impact on precision – is removed, and small changes preserving total sample size are made until no further improvement in precision can be found. Results Striking patterns emerge. Solutions typically focus recruitment and cross-over on the leading diagonal of the cluster-by-time diagram, but in some scenarios clusters form distinct phases resembling before-and-after designs. Conclusions There is much to be learned about optimal design for incomplete stepped wedge trials. Algorithmic searches could offer a practical approach to trial design in complex settings generally.
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spelling doaj.art-2280a24f605940c5afb0536fc1c8ac422022-12-22T00:57:30ZengBMCBMC Medical Research Methodology1471-22882020-11-012011910.1186/s12874-020-01155-zThe hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measuresRichard Hooper0Jessica Kasza1Andrew Forbes2Queen Mary University of LondonMonash UniversityMonash UniversityAbstract Background We consider the design of stepped wedge trials with continuous recruitment and continuous outcome measures. Suppose we recruit from a fixed number of clusters where eligible participants present continuously, and suppose we have fine control over when each cluster crosses to the intervention. Suppose also that we want to minimise the number of participants, leading us to consider “incomplete” designs (i.e. without full recruitment). How can we schedule recruitment and cross-over at different clusters to recruit efficiently while achieving good precision? Methods The large number of possible designs can make exhaustive searches impractical. Instead we consider an algorithm using iterative improvements to hunt for an efficient design. At each iteration (starting from a complete design) a single participant – the one with the smallest impact on precision – is removed, and small changes preserving total sample size are made until no further improvement in precision can be found. Results Striking patterns emerge. Solutions typically focus recruitment and cross-over on the leading diagonal of the cluster-by-time diagram, but in some scenarios clusters form distinct phases resembling before-and-after designs. Conclusions There is much to be learned about optimal design for incomplete stepped wedge trials. Algorithmic searches could offer a practical approach to trial design in complex settings generally.http://link.springer.com/article/10.1186/s12874-020-01155-zAlgorithmsCluster randomised trialsContinuous recruitmentEfficient designStepped wedge trials
spellingShingle Richard Hooper
Jessica Kasza
Andrew Forbes
The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
BMC Medical Research Methodology
Algorithms
Cluster randomised trials
Continuous recruitment
Efficient design
Stepped wedge trials
title The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
title_full The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
title_fullStr The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
title_full_unstemmed The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
title_short The hunt for efficient, incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
title_sort hunt for efficient incomplete designs for stepped wedge trials with continuous recruitment and continuous outcome measures
topic Algorithms
Cluster randomised trials
Continuous recruitment
Efficient design
Stepped wedge trials
url http://link.springer.com/article/10.1186/s12874-020-01155-z
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