Emily C Voldal1, Navneet R Hakhu2, Fan Xia3, Patrick J Heagerty3, James P Hughes3. 1. Department of Biostatistics, University of Washington, Box 357232, Seattle, WA 98195, United States. Electronic address: voldal@uw.edu. 2. Department of Statistics, University of California, Irvine, Irvine, CA 92697, United States. 3. Department of Biostatistics, University of Washington, Box 357232, Seattle, WA 98195, United States.
Abstract
BACKGROUND AND OBJECTIVE: Stepped wedge trials (SWTs) are a type of cluster-randomized trial that are commonly used to evaluate health care interventions. Most SWT-related software packages have restrictive assumptions about the study design and correlation structure of the data. The objective of this paper is to present a package and corresponding web-based graphical user interface (GUI) that provide researchers with another, more flexible option for SWT design and analysis. METHODS: We developed an Rpackage swCRTdesign ('stepped wedge Cluster Randomized Trial design'), which uses a random effects model to account for correlation in the data induced by a SWT design. Possible sources of correlation include clusters, time within clusters, and treatment within clusters. RESULTS: swCRTdesign allows a user to calculate power, simulate SWT data to streamline simulation studies (e.g. to estimate power), and create descriptive summaries and plots. Additionally, a GUI, developed using shiny, is available to calculate power and create power curves and design plots. CONCLUSIONS: The swCRTdesign package accommodates a wide variety of SWT designs, and makes it easy to account for some sources of correlation which are not found in other packages. The user-friendly web-based GUI makes some swCRTdesign features accessible to researchers not familiar with R. These two resources will make appropriately complex SWT calculations more accessible to scientists from a wide variety of backgrounds.
BACKGROUND AND OBJECTIVE: Stepped wedge trials (SWTs) are a type of cluster-randomized trial that are commonly used to evaluate health care interventions. Most SWT-related software packages have restrictive assumptions about the study design and correlation structure of the data. The objective of this paper is to present a package and corresponding web-based graphical user interface (GUI) that provide researchers with another, more flexible option for SWT design and analysis. METHODS: We developed an Rpackage swCRTdesign ('stepped wedge Cluster Randomized Trial design'), which uses a random effects model to account for correlation in the data induced by a SWT design. Possible sources of correlation include clusters, time within clusters, and treatment within clusters. RESULTS: swCRTdesign allows a user to calculate power, simulate SWT data to streamline simulation studies (e.g. to estimate power), and create descriptive summaries and plots. Additionally, a GUI, developed using shiny, is available to calculate power and create power curves and design plots. CONCLUSIONS: The swCRTdesign package accommodates a wide variety of SWT designs, and makes it easy to account for some sources of correlation which are not found in other packages. The user-friendly web-based GUI makes some swCRTdesign features accessible to researchers not familiar with R. These two resources will make appropriately complex SWT calculations more accessible to scientists from a wide variety of backgrounds.
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Authors: Karla Hemming; Monica Taljaard; Joanne E McKenzie; Richard Hooper; Andrew Copas; Jennifer A Thompson; Mary Dixon-Woods; Adrian Aldcroft; Adelaide Doussau; Michael Grayling; Caroline Kristunas; Cory E Goldstein; Marion K Campbell; Alan Girling; Sandra Eldridge; Mike J Campbell; Richard J Lilford; Charles Weijer; Andrew B Forbes; Jeremy M Grimshaw Journal: BMJ Date: 2018-11-09