Cluster randomized trials THEME 1: Cluster randomized trials Charles Weijer Department Here

Cluster randomized trials CRTs are commonly used in knowledge translation, public health and health services research CRTs are experiments in which groups of individuals ─ rather than independent individuals ─ are randomly allocated to interventions Common clusters in health research: Medical practices Hospitals, nursing homes Housing units, neighbourhoods, communities. Ethical issues in cluster randomized trials

Cluster randomized trials Units of randomization are groups rather than individuals Study intervention may be delivered to: the cluster as a unit (cluster-cluster trial) health professionals (professional-cluster trial) individual cluster members (individual-cluster trial) Outcomes are measured on individuals. Ethical issues in cluster randomized trials

Ethical issues in cluster randomized trials

Why do CRTs raise ethical issues? Cluster randomized trials pose difficult ethical issues because of features of their design CRTs involve groups rather than individuals The units of randomization, intervention, and outcome assessment differ within any given trial Clusters may be randomized before cluster members can be approached for informed consent Intervention may be directed at the level of the individual or the level of the cluster. Ethical issues in cluster randomized trials

Ethical issues When is a cluster randomized design justified? Who are the research participants? From whom, how and when must informed consent be obtained? Who are gatekeepers and what are their responsibilities? Does clinical equipoise apply? How do we determine if study benefits outweigh harms? Who is vulnerable and what protections are needed? Ethical issues in cluster randomized trials

Ethical issues in cluster randomized trials