Intracluster correlation coefficients from school-based cluster randomized trials of interventions for improving health outcomes in pupils

Kitty Parker; Michael Nunns; ZhiMin Xiao; Tamsin Ford; Obioha C Ukoumunne

doi:10.1016/j.jclinepi.2023.03.020

Intracluster correlation coefficients from school-based cluster randomized trials of interventions for improving health outcomes in pupils

J Clin Epidemiol. 2023 Jun:158:18-26. doi: 10.1016/j.jclinepi.2023.03.020. Epub 2023 Mar 28.

Authors

Kitty Parker¹, Michael Nunns², ZhiMin Xiao³, Tamsin Ford⁴, Obioha C Ukoumunne⁵

Affiliations

¹ NIHR Applied Research Collaboration South West Peninsula, Department of Health and Community Sciences, Faculty of Health and Life Sciences, University of Exeter, Room 2.16, South Cloisters, St Luke's Campus, 79 Heavitree Rd, Exeter EX1 2LU, UK. Electronic address: [email protected].
² Faculty of Health and Life Sciences, University of Exeter, St Luke's Campus, Heavitree Road, Exeter EX1 2LU, UK.
³ School of Health and Social Care, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
⁴ Department of Psychiatry, University of Cambridge, L5 Clifford Allbutt Building, Cambridge Biomedical Campus Box 58, Cambridge CB2 0AH, UK.
⁵ NIHR Applied Research Collaboration South West Peninsula, Department of Health and Community Sciences, Faculty of Health and Life Sciences, University of Exeter, Room 2.16, South Cloisters, St Luke's Campus, 79 Heavitree Rd, Exeter EX1 2LU, UK.

PMID: 36997102
DOI: 10.1016/j.jclinepi.2023.03.020

Abstract

Background and objectives: To summarize intracluster correlation coefficient (ICC) estimates for pupil health outcomes from school-based cluster randomized trials (CRTs) across world regions and describe their relationship with study design characteristics and context.

Methods: School-based CRTs reporting ICCs for pupil health outcomes were identified through a literature search of MEDLINE (via Ovid). ICC estimates were summarized both overall and for different categories of study characteristics.

Results: Two hundred and forty-six articles reporting ICC estimates were identified. The median (interquartile range) ICC was 0.031 (0.011 to 0.08) at the school level (N = 210) and 0.063 (0.024 to 0.1) at the class level (N = 46). The distribution of ICCs at the school level was well described by the beta and exponential distributions. Besides larger ICCs in definitive trials than feasibility studies, there were no clear associations between study characteristics and ICC estimates.

Conclusion: The distribution of school-level ICCs worldwide was similar to previous summaries from studies in the United States. The description of the distribution of ICCs will help to inform sample size calculations and assess their sensitivity when designing future school-based CRTs of health interventions.

Keywords: Children; Cluster randomized trials; Intracluster correlation coefficient; Public health; Randomized trials; Schools.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cluster Analysis
Humans
Outcome Assessment, Health Care*
Randomized Controlled Trials as Topic
Research Design*
Sample Size