Unequal cluster sizes in stepped-wedge cluster randomised trials: a systematic review

Kristunas, Caroline; Morris, Tom; Gray, Laura J.

doi:10.1136/bmjopen-2017-017151

Cited by 19 publications

(27 citation statements)

References 21 publications

(35 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although stepped-wedge randomised controlled trials are becoming increasingly popular,32, 33 this trial was unusual in being undertaken across multiple countries and presents valuable learning for others planning multi-country stepped-wedge randomised controlled trials. We can only identify one published trial undertaken in multiple countries (in Europe) 34 .…”

Section: Discussionmentioning

confidence: 99%

Effect of a novel vital sign device on maternal mortality and morbidity in low-resource settings: a pragmatic, stepped-wedge, cluster-randomised controlled trial

Vousden

Lawley

Seed

et al. 2019

The Lancet Global Health

View full text Add to dashboard Cite

Summary Background In 2015, an estimated 303 000 women died in pregnancy and childbirth. Obstetric haemorrhage, sepsis, and hypertensive disorders of pregnancy account for more than 50% of maternal deaths worldwide. There are effective treatments for these pregnancy complications, but they require early detection by measurement of vital signs and timely administration to save lives. The primary aim of this trial was to determine whether implementation of the CRADLE Vital Sign Alert and an education package into community and facility maternity care in low-resource settings could reduce a composite of all-cause maternal mortality or major morbidity (eclampsia and hysterectomy). Methods We did a pragmatic, stepped-wedge, cluster-randomised controlled trial in ten clusters across Africa, India, and Haiti, introducing the device into routine maternity care. Each cluster contained at least one secondary or tertiary hospital and their main referral facilities. Clusters crossed over from existing routine care to the CRADLE intervention in one of nine steps at 2-monthly intervals, with CRADLE devices replacing existing equipment at the randomly allocated timepoint. A computer-generated randomly allocated sequence determined the order in which the clusters received the intervention. Because of the nature of the intervention, this trial was not masked. Data were gathered monthly, with 20 time periods of 1 month. The primary composite outcome was at least one of eclampsia, emergency hysterectomy, and maternal death. This study is registered with the ISRCTN registry, number ISRCTN41244132. Findings Between April 1, 2016, and Nov 30, 2017, among 536 223 deliveries, the primary outcome occurred in 4067 women, with 998 maternal deaths, 2692 eclampsia cases, and 681 hysterectomies. There was an 8% decrease in the primary outcome from 79·4 per 10 000 deliveries pre-intervention to 72·8 per 10 000 deliveries post-intervention (odds ratio [OR] 0·92, 95% CI 0·86–0·97; p=0·0056). After planned adjustments for variation in event rates between and within clusters over time, the unexpected degree of variability meant we were unable to judge the benefit or harms of the intervention (OR 1·22, 95% CI 0·73–2·06; p=0·45). Interpretation There was an absolute 8% reduction in primary outcome during the trial, with no change in resources or staffing, but this reduction could not be directly attributed to the intervention due to variability. We encountered unanticipated methodological challenges with this trial design, which can provide valuable learning for future research and inform the trial design of future international stepped-wedge trials. Funding Newton Fund Global Research Programme: UK Medical Research Council; Department of Biotechnology, Ministry of Science & Technology, Government of India; and UK Department of International Development.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of a novel vital sign device on maternal mortality and morbidity in low-resource settings: a pragmatic, stepped-wedge, cluster-randomised controlled trial

Vousden

Lawley

Seed

et al. 2019

The Lancet Global Health

View full text Add to dashboard Cite

show abstract

“…For instance, a recent review study on SW-CRTs identified that approximately half of the 101 designs had unequal cluster sizes. 20 For SW-CRT with unbalanced cluster sizes, sample size and power calculation can be based on either adjusted design effect, 21,22 or F I G U R E 5 Power for testing single intervention effect using Bonferroni's correction and combined effect of all interventions simulation studies. 23,24 Other than unbalanced cluster size, unbalanced sequence size is often related to optimal allocation.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…SW‐CRTs with unbalanced cluster sizes is commonly used in real applications. For instance, a recent review study on SW‐CRTs identified that approximately half of the 101 designs had unequal cluster sizes 20 . For SW‐CRT with unbalanced cluster sizes, sample size and power calculation can be based on either adjusted design effect, 21,22 or simulation studies 23,24 .…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Variance formulae for multiphase stepped wedge cluster randomized trial

Zhang

Shoben

Jackson

et al. 2020

Statistics in Medicine

View full text Add to dashboard Cite

In a multiphase stepped wedge cluster randomized trial (MSW-CRT), more than one intervention will be initiated on each sequence in a fixed order. Hence, with the MSW-CRT design, the effect of the first intervention can be evaluated when compared to control, as well as the added-on effects of the subsequent interventions. Studies that use MSW-CRT have been proposed, but properties of this design have not been explicitly studied. We derive closed-form variance formulae to test the interventions' effects, which can be readily used for sample size and power calculation. Additionally, we provide relationships between variances to test the interventions' effects and design parameters. Under special conditions, some important properties include: (i) the variances to test different interventions' effects (ie, the first intervention effect and the second intervention effect) may be same; (ii) as the cluster-period mean autocorrelation increases, the variance to test an intervention effect may first increase and then decrease; (iii) as the amount of periods between the initiations of two interventions (ie, lag) increases, the variance to test an intervention effect may remain unchanged. We illustrate the relationships between power and design parameters using the variance formulae. From a few illustrative examples, we observe that the statistical test that uses data only relevant to a specific intervention has inferior power (relative power loss <15%) compared to the test when using all the study data. Also, power is reduced when both the total number of periods and lag are decreased simultaneously (relative power loss <20%).

show abstract

“…We will use an adaptation of three previously published search strategies of systematic reviews on stepped wedge design [7,19,57,58]. We will search the following databases up to 16 October 2020: PubMed, Embase, PsycINFO, Web of Science, CINAHL, Cochrane Library and Current Controlled Trials Register.…”

Section: Information Sources and Search Strategymentioning

confidence: 99%

Prevalence and Methodological Characteristics of Subgroup Analyses in Stepped Wedge Cluster Randomised Trials: Protocol for a Systematic Review

Adisso

Taljaard

Rivest

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: The stepped wedge cluster randomised trial is an increasingly common trial design. The design can be useful for informing real-world clinical decision-making, including decisions about the effectiveness of interventions in particular subgroups. However, there is little existing guidance about how to perform subgroup analyses in the stepped wedge design. We aim to determine the prevalence of subgroup analyses and describe statistical methods used to perform them in stepped wedge cluster randomised trials.Methods: We will conduct a systematic review following the methodology recommended in the Cochrane Handbook for Systematic Reviews of Interventions. We report this protocol according to the PRISMA-P checklist. The protocol has been registered in the Open Science Framework. We will search for terms related to ‘stepped wedge’. Sources will be PubMed, Embase, PsycINFO, Web of Science, CINAHL, Cochrane Library, and Current Controlled Trials Register up to 16 October 2020. Studies will be eligible if they are written in English, involve human participants and are primary or secondary reports of planned or completed stepped wedge cluster randomised trials. Two reviewers will first screen the titles and abstracts, then full texts, to select studies that should be included in the review. Disagreements will be solved by consensus through discussion with a third reviewer. We will extract data related to study characteristics including presence or absence of subgroup analyses, characteristics of subgroup variables examined, statistical methods used to perform subgroup analyses, and adherence to the most consistently recommendations suggested for subgroup analyses in general including in clinical trials. We will perform a qualitative synthesis of the extracted data.Discussion: This protocol offers a reproducible and transparent procedure for a systematic review of the literature. It will provide a portrait of the frequency and types of subgroup analyses performed in stepped wedge cluster randomised trials. These results will inform the development of recommendations for subgroup analyses in such trials.Systematic review registration: This protocol has been registered on Open Science Framework, Registration ID: https://osf.io/2kwrz.

show abstract

Unequal cluster sizes in stepped-wedge cluster randomised trials: a systematic review

Cited by 19 publications

References 21 publications

Effect of a novel vital sign device on maternal mortality and morbidity in low-resource settings: a pragmatic, stepped-wedge, cluster-randomised controlled trial

Effect of a novel vital sign device on maternal mortality and morbidity in low-resource settings: a pragmatic, stepped-wedge, cluster-randomised controlled trial

Variance formulae for multiphase stepped wedge cluster randomized trial

Prevalence and Methodological Characteristics of Subgroup Analyses in Stepped Wedge Cluster Randomised Trials: Protocol for a Systematic Review

Contact Info

Product

Resources

About