Dataset Information

A method to reduce imbalance for site-level randomized stepped wedge implementation trial designs.

ABSTRACT: BACKGROUND:Controlled implementation trials often randomize the intervention at the site level, enrolling relatively few sites (e.g., 6-20) compared to trials that randomize by subject. Trials with few sites carry a substantial risk of an imbalance between intervened (cases) and non-intervened (control) sites in important site characteristics, thereby threatening the internal validity of the primary comparison. A stepped wedge design (SWD) staggers the intervention at sites over a sequence of times or time waves until all sites eventually receive the intervention. We propose a new randomization method, sequential balance, to control time trend in site allocation by minimizing sequential imbalance across multiple characteristics. We illustrate the new method by applying it to a SWD implementation trial. METHODS:The trial investigated the impact of blended internal-external facilitation on the establishment of evidence-based teams in general mental health clinics in nine US Department of Veterans Affairs medical centers. Prior to randomization to start time, an expert panel of implementation researchers and health system program leaders identified by consensus a series of eight facility-level characteristics judged relevant to the success of implementation. We characterized each of the nine sites according to these consensus features. Using a weighted sum of these characteristics, we calculated imbalance scores for each of 1680 possible site assignments to identify the most sequentially balanced assignment schemes. RESULTS:From 1680 possible site assignments, we identified 34 assignments with minimal imbalance scores, and then randomly selected one assignment by which to randomize start time. Initially, the mean imbalance score was 3.10, but restricted to the 34 assignments, it declined to 0.99. CONCLUSIONS:Sequential balancing of site characteristics across groups of sites in the time waves of a SWD strengthens the internal validity of study conclusions by minimizing potential confounding. TRIAL REGISTRATION:Registered at ClinicalTrials.gov as clinical trials # NCT02543840 ; entered 9/4/2015.

SUBMITTER: Lew RA

PROVIDER: S-EPMC6500026 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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A method to reduce imbalance for site-level randomized stepped wedge implementation trial designs.

Lew Robert A RA Miller Christopher J CJ Kim Bo B Wu Hongsheng H Stolzmann Kelly K Bauer Mark S MS

Implementation science : IS 20190503 1

<h4>Background</h4>Controlled implementation trials often randomize the intervention at the site level, enrolling relatively few sites (e.g., 6-20) compared to trials that randomize by subject. Trials with few sites carry a substantial risk of an imbalance between intervened (cases) and non-intervened (control) sites in important site characteristics, thereby threatening the internal validity of the primary comparison. A stepped wedge design (SWD) staggers the intervention at sites over a sequen ...[more]

PMID: 31053157

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Project description:BackgroundStepped-wedge cluster randomized trials (SWCRTs) are a type of cluster-randomized trial in which clusters are randomized to cross-over to the active intervention sequentially at regular intervals during the study period. For SWCRTs, sequential imbalances of cluster-level characteristics across the random sequence of clusters may lead to biased estimation. Our study aims to examine the effects of balancing cluster-level characteristics in SWCRTs.MethodsTo quantify the level of cluster-level imbalance, a novel imbalance index was developed based on the Spearman correlation and rank regression of the cluster-level characteristic with the cross-over timepoints. A simulation study was conducted to assess the impact of sequential cluster-level imbalances across different scenarios varying the: number of sites (clusters), sample size, number of cross-over timepoints, site-level intra-cluster correlation coefficient (ICC), and effect sizes. SWCRTs assumed either an immediate "constant" treatment effect, or a gradual "learning" treatment effect which increases over time after crossing over to the active intervention. Key performance metrics included the relative root mean square error (RRMSE) and relative mean bias.ResultsFully-balanced designs almost always had the highest efficiency, as measured by the RRMSE, regardless of the number of sites, ICC, effect size, or sample sizes at each time for SWCRTs with learning effect. A consistent decreasing trend of efficiency was observed by increasing RRMSE as imbalance increased. For example, for a 12-site study with 20 participants per site/timepoint and ICC of 0.10, between the most balanced and least balanced designs, the RRMSE efficiency loss ranged from 52.5% to 191.9%. In addition, the RRMSE was decreased for larger sample sizes, larger number of sites, smaller ICC, and larger effect sizes. The impact of pre-balancing diminished when there was no learning effect.ConclusionThe impact of pre-balancing on preventing efficiency loss was easily observed when there was a learning effect. This suggests benefit of pre-balancing with respect to impacting factors of treatment effects.

Project description:BACKGROUND:Stepped wedge cluster randomized trials (SW-CRT) are increasingly used to evaluate new clinical programs, yet there is limited guidance on practical aspects of applying this design. We report our early experiences conducting a SW-CRT to examine an inpatient mobility program (STRIDE) in the Veterans Health Administration (VHA). We provide recommendations for future research using this design to evaluate clinical programs. METHODS:Based on data from study records and reflections from the investigator team, we describe and assess the design and initial stages of a SW-CRT, from site recruitment to program launch in 8 VHA hospitals. RESULTS:Site recruitment consisted of thirty 1-h conference calls with representatives from 22 individual VAs who expressed interest in implementing STRIDE. Of these, 8 hospitals were enrolled and randomly assigned in two stratified blocks (4 hospitals per block) to a STRIDE launch date. Block 1 randomization occurred in July 2017 with first STRIDE launch in December 2017; block 2 randomization occurred in April 2018 with first STRIDE launch in January 2019. The primary study outcome of discharge destination will be assessed using routinely collected data in the electronic health record (EHR). Within randomized blocks, two hospitals per sequence launched STRIDE approximately every 3?months with primary outcome assessment paused during the 3-month time period of program launch. All sites received 6-8 implementation support calls, according to a pre-specified schedule, from the time of recruitment to program launch, and all 8 sites successfully launched within their assigned 3-month window. Seven of the eight sites initially started with a limited roll out (for example on one ward) or modified version of STRIDE (for example, using existing staff to conduct walks until new positions were filled). CONCLUSIONS:Future studies should incorporate sufficient time for site recruitment and carefully consider the following to inform design of SW-CRTs to evaluate rollout of a new clinical program: (1) whether a blocked randomization fits study needs, (2) the amount of time and implementation support sites will need to start their programs, and (3) whether clinical programs are likely to include a "ramp-up" period. Successful execution of SW-CRT designs requires both adherence to rigorous design principles and also careful consideration of logistical requirements for timing of program roll out. TRIAL REGISTRATION:ClinicalsTrials.gov NCT03300336 . Prospectively registered on 3 October 2017.

Dataset Information

A method to reduce imbalance for site-level randomized stepped wedge implementation trial designs.

Publications

A method to reduce imbalance for site-level randomized stepped wedge implementation trial designs.

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