Select campus:UKDubai
University of Birmingham
Menu
Five groups of coloured wooden skittles in clusters of 5

CLUB (CLuster trials at University of Birmingham)

Five groups of coloured wooden skittles in clusters of 5

Cluster randomised trials (CRTs) evaluate interventions delivered to groups—such as hospitals, schools or communities—rather than individuals. These designs are widely used to evaluate complex healthcare and public health interventions, particularly when interventions are implemented at the organisational or system level.

  • Blue, red and yellow squares form a larger square. CLUB, Cluster Trials logo

    Researchers at University of Birmingham develop statistical methodology and collaborate on applied research to improve the design, analysis and reporting of cluster and stepped-wedge trials. The group combines methodological research with collaboration on applied trials across healthcare systems, public health, and implementation science.

Our work focuses on improving the design, analysis, and reporting of cluster and stepped-wedge randomised trials. Key areas include:

  • Design and analysis methods for stepped-wedge cluster trials
  • Optimal design of cluster randomised trials
  • Statistical modelling for clustered and longitudinal trial data
  • Methodological guidance for reporting complex trial designs
  • Evaluation of complex healthcare and public health interventions

Meet the team

  • Professor Karla Hemming

    Professor of Biostatistics

    Professor Karla Hemming is a Professor of Biostatics in the Department of Applied Health Sciences.

Professor of Biostatistics specialising in the design, conduct, and analysis of cluster and stepped-wedge randomised trials. Her work focuses on improving statistical methodology and reporting standards for complex trial designs and supporting the evaluation of healthcare and public health interventions.

  • Professor Sam Watson

    Professor of Biostatistics

    Staff profile page for Sam Watson, Senior Lecturer at the Department of Applied Health Sciences.

Professor of Biostatistics whose research focuses on optimal design strategies for cluster randomised trials. His work develops computational and statistical methods for efficient trial design and analysis of correlated data in health research.

  • Dr James Martin

    Associate Professor of Biostatistics

    Dr James Martin's research focuses on improving the design, conduct and analysis of studies involving clustered data.

Associate Professor in Biostatistics specialising in cluster randomised trials and stepped-wedge designs. His research focuses on trial monitoring, methodological challenges, and the application of these designs in large pragmatic healthcare studies.

  • Mrs Christina Easter

    Assistant Professor

    Staff profile for Miss Christina Easter, Assistant Professor in the Department of Applied Health Sciences, University of Birmingham.

Christina is a current PhD student and Assistant Professor with a research focus in cluster randomised trials (CRTs). She is currently in the final year of her PhD and is preparing to submit her thesis, “Risk of biases in Cluster randomised trials”, later this year.

Her expertise spans methodological research in CRTs, including identification and recruitment bias through simulation studies and qualitative research. Additionally, she has experience in CRT sample size calculations, systematic reviews of CRTs and completing the statistical analysis of both parallel and stepped wedge CRTs.

Her current research is focused on advancing prediction modelling under the CRT design.

  • Dr Laura Quinn

    Research Fellow in Medical Statistics

    Staff profile for Laura Quinn, BESaTE team, Medical Statistician in the Department of Applied Health Sciences, University of Birmingham.

Medical statistician contributing to trial design, statistical analysis and methodological research within the biostatistics group. Her research focuses on evaluating complex healthcare interventions using interrupted time series, which share methodological foundations with multiple-period cluster randomised trials.

  • Miss Jacqueline Thompson

    Research Fellow

    Staff profile for Jacqueline Thompson, Research Fellow, Department of Applied Health Sciences, University of Birmingham

Researcher specialising in clinical trials methodology and statistical analysis. She contributes to research on reporting standards and methodological improvements for cluster and stepped-wedge trials.

  • Dr Yixin Wang

    Research Fellow

    Staff profile for Dr Yixin Wang, Research Fellow in the Department of Applied Health Sciences, College of Medicine and Health, University of Birmingham.

Statistician working on methodological development for cluster randomised trials and related study designs. Her research focuses on statistical modelling approaches for clustered and longitudinal health data.

The Cluster Trials Methodology group are part of BESTEAM. Please contact Hayley Walton (Senior Administrator) for further information.

BESTEAM staff

Example projects

Members of the group contribute to the design, analysis and methodological development of cluster randomised trials across a wide range of public health and healthcare settings. These include trials conducted in schools, hospitals and health systems internationally. Below are examples of cluster trials involving members of the group.

 

Daily Mile Trial

Lead institution: University of Birmingham

Design: Parallel-arm cluster randomised trial

The Daily Mile trial evaluated a school-based physical activity intervention designed to increase children’s daily exercise through a simple programme of 15 minutes of running or walking during the school day. In this parallel-arm cluster randomised trial, 40 primary schools in Birmingham were randomised to either implement The Daily Mile or continue usual practice. The study assessed outcomes including body mass index, physical fitness and wellbeing among children aged 7–10 years. The trial aimed to determine whether this easily implementable intervention could improve children’s health and wellbeing and inform public health policy on physical activity in schools. 

Reference: Breheny, K., Passmore, S., Adab, P., Martin, J., Hemming, K., Lancashire, E.R. and Frew, E., 2020. Effectiveness and cost-effectiveness of The Daily Mile on childhood weight outcomes and wellbeing: a cluster randomised controlled trial. International Journal of Obesity, 44(4), pp.812-822.

 

WAVES Study

Lead institution: University of Birmingham

Design: Parallel-arm cluster randomised trial

The WAVES study evaluated a multi-component school-based programme designed to prevent childhood obesity. In this parallel-arm cluster randomised trial, primary schools were allocated to either deliver the intervention – which included physical activity sessions, cooking workshops, and family engagement activities – or continue their usual curriculum. The study measured outcomes including body mass index and lifestyle behaviours among children aged 6–7 years. The trial aimed to assess whether structured school-based programmes could improve health behaviours and help reduce childhood obesity.

Reference: Adab, P., Pallan, M.J., Lancashire, E.R., Hemming, K., Frew, E., Barrett, T., Bhopal, R., Cade, J.E., Canaway, A., Clarke, J.L. and Daley, A., 2018. Effectiveness of a childhood obesity prevention programme delivered through schools, targeting 6 and 7 year olds: cluster randomised controlled trial (WAVES study). BMJ, 360.

 

E-MOTIVE

Lead institutions: University of Birmingham and the World Health Organization

Design: Parallel-arm cluster randomised trial with baseline period

The E-MOTIVE trial evaluated a package of interventions designed to improve the early detection and treatment of postpartum haemorrhage, one of the leading causes of maternal mortality worldwide. In this parallel-arm cluster randomised trial with a baseline period, hospitals implemented either a protocol involving routine measurement of blood loss together with a rapid treatment bundle, or continued standard care. The trial measured outcomes including severe postpartum haemorrhage and related maternal complications. The study aimed to determine whether earlier recognition and coordinated treatment could reduce maternal morbidity and mortality across diverse health system settings.

Reference: Gallos, I., Devall, A., Martin, J., Middleton, L., Beeson, L., Galadanci, H., Alwy Al-beity, F., Qureshi, Z., Hofmeyr, G.J., Moran, N. and Fawcus, S., 2023. Randomized trial of early detection and treatment of postpartum hemorrhage. New England Journal of Medicine, 389(1), pp.11-21.

 

APT-Sepsis

Lead institution: University of Liverpool

Statistical oversight: University of Birmingham

Design: Parallel-arm cluster randomised trial with baseline period

The APT-Sepsis trial evaluated a multi-component intervention designed to improve the prevention and management of maternal infection and sepsis in maternity care settings. In this parallel-arm cluster randomised trial with a baseline period, health facilities implemented a package of measures including infection prevention practices, improved hand hygiene and a treatment bundle for early recognition and management of maternal sepsis, or continued usual care. The study assessed outcomes including infection-related maternal morbidity and mortality. The trial aimed to determine whether strengthening infection prevention and early treatment systems could improve maternal outcomes.

Reference: Lissauer, D., Gadama, L., Waitt, C., Whyte, S., Burnside, G., Anilkumar, A., Makuluni, R., Okwaro, P., Yang, L., Waitt, P. and Musopole, O., 2025. A multicomponent intervention to improve maternal infection outcomes. New England Journal of Medicine.

 

IC3D Trial

Lead institution: Boston University

Statistical oversight: University of Birmingham

Design: Stepped-wedge cluster randomised trial

The IC3D trial evaluated an integrated model of care for depression within chronic disease services in Malawi. In this stepped-wedge cluster randomised trial, health facilities sequentially introduced a programme integrating mental health screening and treatment into routine care for patients with chronic conditions. The trial assessed outcomes including symptoms of depression and patient functioning. The study aimed to determine whether integrating mental health care into existing health services could improve patient outcomes in low-resource settings.

Reference: McBain, R.K., Mwale, O., Mpinga, K., Kamwiyo, M., Kayira, W., Ruderman, T., Connolly, E., Watson, S.I., Wroe, E.B., Munyaneza, F. and Dullie, L., 2024. Effectiveness, cost-effectiveness, and positive externalities of integrated chronic care for adults with major depressive disorder in Malawi (IC3D): a stepped-wedge, cluster-randomised, controlled trial. The Lancet, 404(10465), pp.1823-1834.

Affiliated centres

Workshops, conferences and seminars

The team contributes to international training and knowledge exchange through workshops and seminars on:

  • Cluster randomised trial design
  • Stepped-wedge trial methodology

Collaboration and opportunities

The group welcomes collaborations with researchers planning or conducting cluster randomised trials. We provide expertise in study design, statistical analysis, and trial methodology across a wide range of healthcare and public health settings.

We also welcome enquiries from prospective PhD students and researchers interested in methodological or applied research in cluster trials.

Please contact Hayley Walton (Senior Administrator).

Key publications

Methods Research

CONSORT extension for stepped-wedge trials

This paper extends the CONSORT reporting guidelines to stepped-wedge cluster randomised trials, providing recommendations to improve transparency and completeness when reporting these complex study designs.

Reference: Hemming, K., Taljaard, M., McKenzie, J.E., Hooper, R., Copas, A., Thompson, J.A., Dixon-Woods, M., Aldcroft, A., Doussau, A., Grayling, M. and Kristunas, C., 2018. Reporting of stepped wedge cluster randomised trials: extension of the CONSORT 2010 statement with explanation and elaboration. BMJ, 363.

 

Stepped-wedge trial design overview

This highly cited methodological paper provides a comprehensive overview of the rationale, design, analysis, and reporting considerations for stepped-wedge cluster trials.

Reference: Hemming, K., Haines, T.P., Chilton, P.J., Girling, A.J. and Lilford, R.J., 2015. The stepped wedge cluster randomised trial: rationale, design, analysis, and reporting. BMJ, 350.

 

Sample size with fixed clusters

This paper develops methods for calculating sample sizes in cluster randomised trials when the number of clusters is fixed – a common constraint in health services research.

Reference: Hemming, K., Girling, A.J., Sitch, A.J., Marsh, J. and Lilford, R.J., 2011. Sample size calculations for cluster randomised controlled trials with a fixed number of clusters. BMC medical research methodology, 11(1), p.102.

 

Three arm cluster randomised trials

This paper explores statistical design and analysis strategies for three-arm cluster trials when the number of clusters is small.

Reference: Watson, S.I., Girling, A. and Hemming, K., 2021. Design and analysis of three‐arm parallel cluster randomized trials with small numbers of clusters. Statistics in Medicine, 40(5), pp.1133-1146.

 

Optimal designs for cluster randomised trials

This paper reviews approaches for identifying efficient cluster trial designs under various logistical and statistical constraints.

Reference: Watson, S.I., Girling, A. and Hemming, K., 2023. Optimal study designs for cluster randomised trials: An overview of methods and results. Statistical Methods in Medical Research, 32(11), pp.2135-2157.

 

Risk of bias in cluster randomised trials

This Qualitative interview study explores CRT researcher’s opinions on the challenges and solutions on handling selection bias arising within cluster trials.

Reference: Easter CL, Kristunas C, Greenfield S, and Hemming K. Researchers’ views of risk of bias in cluster randomised trials: a qualitative interview study BMJ Open 2025;15:e103091.

Resources

The group develops tools and educational materials to support researchers designing cluster randomised trials. 

We also run a CPD course that provides an introduction into cluster randomised trials: Foundations in Cluster Randomised Trials.

Theme contact