The current use of feasibility studies in the assessment of feasibility for stepped-wedge cluster randomised trials: a systematic review.

BACKGROUND: Stepped-wedge cluster randomised trials (SW-CRTs) are a pragmatic trial design, providing an unprecedented opportunity to increase the robustness of evidence underpinning implementation and quality improvement interventions. Given the complexity of the SW-CRT, the likelihood of trials not delivering on their objectives will be mitigated if a feasibility study precedes the definitive trial. It is not currently known if feasibility studies are being conducted for SW-CRTs nor what the objectives of these studies are. METHODS: Searches were conducted of several databases to identify published feasibility studies which were designed to inform a future SW-CRT. For each eligible study, data were extracted on the characteristics of and rationale for the feasibility study; the process for determining progression to the main trial; how the feasibility study informed the main trial; and whether the main trial went ahead. A narrative synthesis and descriptive analysis are presented. RESULTS: Eleven feasibility studies were identified, which included eight completed study reports and three protocols. Three studies used a stepped-wedge design and these were the only studies to be randomised. Studies were predominantly of a mixed-methods design. Only one study assessed specific features related to the feasibility of using a SW-CRT and one investigated the time taken to complete the study procedures. The other studies were mostly assessing the feasibility and acceptability of the intervention. CONCLUSION: Published feasibility studies for SW-CRTs are scarce and those that are being reported do not investigate issues specific to the complexities of the trial design. When conducting feasibility studies in advance of a definitive SW-CRT, researchers should consider assessing the feasibility of study procedures, particularly those specific to the SW-CRT design, and ensure that the findings are published for the benefit of other researchers.

The impact of an intervention to increase uptake to structured self-management education for people with type 2 diabetes mellitus in primary care (the embedding package), compared to usual care, on glycaemic control: study protocol for a mixed methods study incorporating a wait-list cluster randomised controlled trial.

BACKGROUND: Approximately 425 million people globally have diabetes, with ~ 90% of these having Type 2 Diabetes Mellitus (T2DM). This is a condition that leads to a poor quality of life and increased risk of serious health complications. Structured self-management education (SSME) has been shown to be effective in improving glycaemic control and patient related outcome measures and to be cost-effective. However, despite the demonstrated benefits, attendance at SSME remains low. An intervention has been developed to embed SSME called the 'Embedding Package'. The intervention aims to address barriers and enhance enablers to uptake of SSME at patient, healthcare professional and organisational levels. It comprises a marketing strategy, user friendly and effective referral pathways, new roles to champion SSME and a toolkit of resources. METHODS: A mixed methods study incorporating a wait-list cluster randomised trial and ethnographic study, including 66 UK general practices, will be conducted with two intervention start times (at 0 and 9 months), each followed by an active delivery phase. At 18 months, the intervention will cease to be actively delivered and a 12 month observational follow-up phase will begin. The intervention, the Embedding Package, aims to increase SSME uptake and subsequent improvements in health outcomes, through a clear marketing strategy, user friendly and effective referral pathways, a local clinical champion and an 'Embedder' and a toolkit of resources for patients, healthcare professionals and other key stakeholders. The primary aim is, through increasing uptake to and attendance at SSME, to reduce HbA1c in people with T2DM compared with usual care. Secondary objectives include: assessing whether there is an increase in referral to and uptake of SSME and improvements in biomedical and psychosocial outcomes; an assessment of the sustainability of the Embedding Package; contextualising the process of implementation, sustainability of change and the 'fit' of the Embedding Package; and an assessment of the cost-effectiveness of the Embedding Package. DISCUSSION: This study will assess the effectiveness, cost-effectiveness and sustainability of the Embedding Package, an intervention which aims to improve biomedical and psychosocial outcomes of people with T2DM, through increased referral to and uptake of SSME. TRIAL REGISTRATION: International Standard Randomised Controlled Trials Number ISRCTN23474120. Assigned 05/04/2018. The study was prospectively registered. On submission of this manuscript practice recruitment is complete, participant recruitment is ongoing and expected to be completed by the end of 2019.

Increasing uptake of structured self-management education programmes for type 2 diabetes in a primary care setting: a feasibility study.

BACKGROUND: Structured self-management education (SSME) for people with type 2 diabetes mellitus (T2DM) improves biomedical and psychological outcomes, whilst being cost-effective. Yet uptake in the UK remains low. An 'Embedding Package' addressing barriers and enablers to uptake at patient, health care professional and organisational levels has been developed. The aim of this study was to test the feasibility of conducting a subsequent randomised controlled trial (RCT) to evaluate the Embedding Package in primary care, using a mixed methods approach. METHODS: A concurrent mixed methods approach was adopted. Six general practices in the UK were recruited and received the intervention (the Embedding Package). Pseudonymised demographic, biomedical and SSME data were extracted from primary care medical records for patients recorded as having a diagnosis of T2DM. Descriptive statistics assessed quantitative data completeness and accuracy. Quantitative data were supplemented and validated by a patient questionnaire, for which two recruitment methods were trialled. Where consent was given, the questionnaire and primary care data were linked and compared. The cost of the intervention was estimated. An integrated qualitative study comprising ethnography and stakeholder and patient interviews explored the process of implementation, sustainability of change and 'fit' of the intervention. Qualitative data were analysed using a thematic framework guided by the Normalisation Process Theory (NPT). RESULTS: Primary care data were extracted for 2877 patients. The primary outcome for the RCT, HbA1c, was over 90% complete. Questionnaires were received from 423 (14.7%) participants, with postal invitations yielding more participants than general practitioner (GP) prompts. Ninety-one percent of questionnaire participants consented to data linkage. The mean cost per patient for the Embedding Package was £8.94, over a median follow-up of 162.5 days. Removing the development cost, this reduces to £5.47 per patient. Adoption of ethnographic and interview methods in the collection of data was appropriate, and the use of NPT, whilst challenging, enhanced the understanding of the implementation process. The need to delay the collection of patient interview data to enable the intervention to inform patient care was highlighted. CONCLUSIONS: It is feasible to collect data with reasonable completeness and accuracy for the subsequent RCT, although refinement to improve the quality of the data collected will be undertaken. Based on resource use data collected, it was feasible to produce cost estimates for each individual component of the Embedding Package. The methods chosen to generate, collect and analyse qualitative data were satisfactory, keeping participant burden low and providing insight into potential refinements of the Embedding Package and customisation of the methods for the RCT. TRIAL REGISTRATION: ISRCTN, ISRCTN21321635, Registered 07/07/2017-retrospectively registered.

An imbalance in cluster sizes does not lead to notable loss of power in cross-sectional, stepped-wedge cluster randomised trials with a continuous outcome.

BACKGROUND: The current methodology for sample size calculations for stepped-wedge cluster randomised trials (SW-CRTs) is based on the assumption of equal cluster sizes. However, as is often the case in cluster randomised trials (CRTs), the clusters in SW-CRTs are likely to vary in size, which in other designs of CRT leads to a reduction in power. The effect of an imbalance in cluster size on the power of SW-CRTs has not previously been reported, nor what an appropriate adjustment to the sample size calculation should be to allow for any imbalance. We aimed to assess the impact of an imbalance in cluster size on the power of a cross-sectional SW-CRT and recommend a method for calculating the sample size of a SW-CRT when there is an imbalance in cluster size. METHODS: The effect of varying degrees of imbalance in cluster size on the power of SW-CRTs was investigated using simulations. The sample size was calculated using both the standard method and two proposed adjusted design effects (DEs), based on those suggested for CRTs with unequal cluster sizes. The data were analysed using generalised estimating equations with an exchangeable correlation matrix and robust standard errors. RESULTS: An imbalance in cluster size was not found to have a notable effect on the power of SW-CRTs. The two proposed adjusted DEs resulted in trials that were generally considerably over-powered. CONCLUSIONS: We recommend that the standard method of sample size calculation for SW-CRTs be used, provided that the assumptions of the method hold. However, it would be beneficial to investigate, through simulation, what effect the maximum likely amount of inequality in cluster sizes would be on the power of the trial and whether any inflation of the sample size would be required.

The use of feasibility studies for stepped-wedge cluster randomised trials: protocol for a review of impact and scope.

INTRODUCTION: The stepped-wedge cluster randomised trial (SW-CRT) is a complex design, for which many decisions about key design parameters must be made during the planning. These include the number of steps and the duration of time needed to embed the intervention. Feasibility studies are likely to be useful for informing these decisions and increasing the likelihood of the main trial's success. However, the number of feasibility studies being conducted for SW-CRTs is currently unknown. This review aims to establish the number of feasibility studies being conducted for SW-CRTs and determine which feasibility issues are commonly investigated. METHODS AND ANALYSIS: Fully published feasibility studies for SW-CRTs will be identified, according to predefined inclusion criteria, from searches conducted in Ovid MEDLINE, Scopus, Embase and PsycINFO. To also identify and gain information on unpublished feasibility studies the following will be contacted: authors of published SW-CRTs (identified from the most recent systematic reviews); contacts for registered SW-CRTs (identified from clinical trials registries); lead statisticians of UK registered clinical trials units and researchers known to work in the area of SW-CRTs.Data extraction will be conducted independently by two reviewers. For the fully published feasibility studies, data will be extracted on the study characteristics, the rationale for the study, the process for determining progression to a main trial, how the study informed the main trial and whether the main trial went ahead. The researchers involved in the unpublished feasibility studies will be contacted to elicit the same information.A narrative synthesis will be conducted and provided alongside a descriptive analysis of the study characteristics. ETHICS AND DISSEMINATION: This review does not require ethical approval, as no individual patient data will be used. The results of this review will be published in an open-access peer-reviewed journal.