School-level intra-cluster correlation coefficients and autocorrelations for children’s accelerometer-measured physical activity in England by age and gender
Year: 2024
Type: article
Abstract: BACKGROUND: Randomised, cluster-based study designs in schools are commonly used to evaluate children's physical activity interventions. Sample size estimation relies on accurate estimation of the intra-cluster correlation coefficient (ICC), but published estimates, especially using accelerometry-measured physical activity, are few and vary depending on physical activity outcome and participant age. Less commonly-used cluster-based designs, such as stepped wedge designs, also need to account for correlations over time, e.g. cluster autocorrelation (CAC) and individual autocorrelation (IAC), but no estimates are currently available. This paper estimates the school-level ICC, CAC and IAC for England children's accelerometer-measured physical activity outcomes by age group and gender, to inform the design of future school-based cluster trials. METHODS: Data were pooled from seven large English datasets of accelerometer-measured physical activity data between 2002-18 (> 13,500 pupils, 540 primary and secondary schools). Linear mixed effect models estimated ICCs for weekday and whole week for minutes spent in moderate-to-vigorous physical activity (MVPA) and being sedentary for different age groups, stratified by gender. The CAC (1,252 schools) and IAC (34,923 pupils) were estimated by length of follow-up from pooled longitudinal data. RESULTS: School-level ICCs for weekday MVPA were higher in primary schools (from 0.07 (95% CI: 0.05, 0.10) to 0.08 (95% CI: 0.06, 0.11)) compared to secondary (from 0.04 (95% CI: 0.03, 0.07) to (95% CI: 0.04, 0.10)). Girls' ICCs were similar for primary and secondary schools, but boys' were lower in secondary. For all ages, combined the CAC was 0.60 (95% CI: 0.44-0.72), and the IAC was 0.46 (95% CI: 0.42-0.49), irrespective of follow-up time. Estimates were higher for MVPA vs sedentary time, and for weekdays vs the whole week. CONCLUSIONS: Adequately powered studies are important to evidence effective physical activity strategies. Our estimates of the ICC, CAC and IAC may be used to plan future school-based physical activity evaluations and were fairly consistent across a range of ages and settings, suggesting that results may be applied to other high income countries with similar school physical activity provision. It is important to use estimates appropriate to the study design, and that match the intended study population as closely as possible.
Source: BMC Medical Research Methodology
Authors: Ruth Salway, Russell Jago, Frank de Vocht, Danielle House, Alice Porter, Robert Walker, Ruth Kipping, Christopher G. Owen, Mohammed T. Hudda, Kate Northstone, Esther van Sluijs, International Children’s Accelerometry Database (ICAD) Collaborators, Andrew Atkin, Ulf Ekelund, Dale Esliger, Bjorge H. Hansen, Lauren Sherar, Esther van Sluijs
Institutions: University of Bristol, NIHR Bristol Biomedical Research Centre, University Hospitals Bristol and Weston NHS Foundation Trust, NIHR Applied Research Collaboration West, University of London, St George's, University of London, Dasman Diabetes Institute, University of Cambridge, MRC Epidemiology Unit, University of East Anglia, Norwegian School of Sport Sciences, Loughborough University
Language: English
Topic: Physical Activity and Health
Subfield: Physiology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,990
Funders: Wellcome Trust, UK Research and Innovation, Alzheimer's Society, Høgskulen på Vestlandet, Alzheimer's Research Trust, Cancer Research UK, National Institute for Health and Care Research, British Heart Foundation, Department of Health and Social Care, Diabetes UK, Loughborough University, University of Bristol, Public Health Agency, Norges Forskningsråd, Norges Idrettshøgskole, Directorate for Biological Sciences, Medical Research Council, Engineering and Physical Sciences Research Council, Economic and Social Research Council, World Cancer Research Fund, Public Health Research Programme, Health and Social Care Research and Development Division, National Institute for Health Research Applied Research Collaboration West
Awards: G1044355406, G139823147, G1453054114, G1684393010, G1793884970, G2140226292, PROACTIV: PaRental influences On physical ACTIVity and screen-viewing in young children. ,, G2892497062, G3507283293, G3632306667, The Avon Longitudinal Study of Parents and Children (ALSPAC): A multi- generation, longitudinal resource focusing on life course health and well- being., G3987754321, G4389161098, G4723666950, G5490226664, Action330: Promoting children's physical activity via enhanced after-school leadership, G5591412214, Behavioural Epidemiology of Physical Activity, The influence of families and friends on change in physical activity, sedentary behaviour and screen-viewing from Years 1 to 6 in the B-PROACT1V cohort: finding new ways to change behaviour. ,, Active For Life Year 5: A cluster randomised controlled trial of a primary school-based intervention to increase levels of physical activity, decrease sedentary behaviour and improve diet, PASSPORT: A Physical Activity School-Specific PORTfolio intervention evaluated via a stepped wedge design to increase children's physical activity, Ethnicity and cardiovascular risk factors: a study in children., The Avon Longitudinal Study of Parents and Children (ALSPAC): A multi-generation, longitudinal resource focusing on life course health and well-being., Physical activity epidemiology
OpenAlex ID: W4401463998