A Practical Guide to Cluster Randomized Trials in School Health Research

Abstract

BACKGROUND When well‐designed and implemented, cluster randomized trials can meet the high standards federal agencies and other funders increasingly require for evidence on the effectiveness of school health programs and services. However, designing and implementing these studies can present more challenges than at first appears. METHODS I reviewed summaries of the methodological literature on cluster randomized trials. I then conducted a search to identify practical applications of these methods in school health research. RESULTS The review identified 6 key issues or decisions school health researchers must address when designing, conducting, and analyzing data from a cluster randomized trial: (1) reasons to use a clustered design, (2) sample size calculation, (3) the use of matching or stratification, (4) definition of the school and student samples, (5) consent gathering, and (6) analysis methods. CONCLUSIONS School health researchers can take several practical steps to ensure the availability of high‐quality research evidence and meet the growing demands for evidence and accountability in education policy and programming. These steps include selecting the right research design for the intervention and evaluation setting, identifying appropriate sample definitions and analysis methods, and developing appropriate procedures for gathering parental permission and student assent.

Characteristics and practices of school-based cluster randomised controlled trials for improving health outcomes in pupils in the United Kingdom: a methodological systematic review

“…Although the use of CRTs to evaluate the effectiveness of interventions for improving educational outcomes is long established [12,13], their use to evaluate health interventions in schools is more recent [10]. Schools provide a natural environment to recruit, deliver public health interventions to and measure outcomes on children, due to the amount of time they spend there [10]. Cluster randomisation is consistent with the natural clustering found within school settings (i.e., classrooms within year groups within schools).…”

“…CRTs are increasingly used to evaluate non-pharmacological interventions for improving child health outcomes [9][10][11]. Although the use of CRTs to evaluate the effectiveness of interventions for improving educational outcomes is long established [12,13], their use to evaluate health interventions in schools is more recent [10].…”

“…CRTs are increasingly used to evaluate non-pharmacological interventions for improving child health outcomes [9][10][11]. Although the use of CRTs to evaluate the effectiveness of interventions for improving educational outcomes is long established [12,13], their use to evaluate health interventions in schools is more recent [10]. Schools provide a natural environment to recruit, deliver public health interventions to and measure outcomes on children, due to the amount of time they spend there [10].…”

Characteristics and practices of school-based cluster randomised controlled trials for improving health outcomes in pupils in the UK: a systematic review protocol

“…Because of the amount of time children spend in school, it provides a natural setting in which interventions for preventing health problems and improving health outcomes in children can be delivered and evaluated. 13 Cluster randomised controlled trials in the school-based setting are particularly relevant for non-pharmacological interventions, such as social programmes aimed at improving public health 13 and the use of this study design is increasing. 12 Through summarising the methodological aspects of health-related cluster randomised controlled trials conducted in a schools, this review will provide methodology-related knowledge specific to these trials which will help researchers plan future similar studies effectively in the UK and elsewhere.…”

“…12 13 Because of the amount of time children spend in school, it provides a natural setting in which interventions for preventing health problems can be delivered, participating children can be recruited, and health outcomes measured. 13 At a policy level, there is increasing awareness of the potential for using the school setting to deliver, non-pharmacological, complex, prevention public health interventions. 12 14 15 Cluster randomisation is a more natural approach than individual randomisation in the school-based setting.…”