Podcasts for Research Guidance

Chapter 4.3 Cluster randomized trials

Chapter 4.3 explains the role that cluster randomized trials can play in health emergency and disaster risk management (Health EDRM), including:

1. The advantages and disadvantages of the cluster randomized trial methodology.
2. Situations in which cluster randomized trials could be used.
3. Potential difficulties in the implementation of cluster randomized trials and solutions for overcoming them.

What is this chapter about?

In some cases in Health EDRM, it might not be possible or appropriate to carry out an individual randomized trial to resolve uncertainties about the effects of interventions, actions and strategies because the interventions are delivered to groups of people. As an alternative, studies may be designed to randomize groups of participants as “clusters” in a cluster randomized trial.

This chapter describes how cluster randomized trials can be used to evaluate population-level interventions. It provides key information about the design, advantages, disadvantages and analysis considerations for cluster randomized trials. These include issues such as deciding whether a cluster trial is more appropriate than an individually randomised trial, the methods for obtaining informed consent from participants and the need to adjust the analyses to take account of clustering. The chapter contains case studies that describe a novel cluster randomized trial of vaccination against Ebola, and the use of a cluster randomized trial to test village-wide antibiotic prophylaxis for meningococcal meningitis and the informed consent process for this trial in Niger.

Case studies presented in the chapter:

1. A novel cluster randomized design for evaluating Ebola vaccines.
2. Testing a strategy of village-wide antibiotic prophylaxis during a meningococcal meningitis outbreak in the Madarounfa District of Niger.
3. Obtaining permission to participate and the informed consent process in the cluster randomized trial of antibiotic prophylaxis in the Madarounfa District of Niger.

Authors: Coldiron M, Grais RF.