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Table 3 Summary of methodological characteristics of included studies (N = 24)

From: Systematic review of the characteristics of school-based feasibility cluster randomised trials of interventions for improving the health of pupils in the UK

Characteristic N Statistic
Setting
Country 24  
  England, n (%)   18 (75)
  Scotland, n (%)   1 (4)
  Wales, n (%)   2 (8)
  Northern Ireland, n (%)   3 (13)
School types that were included [51][Accessed 1st September 2021] a 15  
  State, n (%)   14 (93)
  Academy, n (%)   3 (20)
  Voluntary aided, n (%)   1 (7)
  Foundation, n (%)   1 (7)
  Faith, n (%)   1 (7)
  Grammar, n (%)   1 (7)
  Independent, n (%)   1 (7)
Intervention
Type of intervention [1] b 24  
  Individual-cluster, n (%)   2 (8)
  Professional-cluster, n (%)   18 (75)
  External-cluster, n (%)   8 (33)
  Cluster–cluster, n (%)   23 (96)
  Multifaceted, n (%)   21 (88)
Intervention componentsc 24  
  Resources and materials for schools, n (%)   11 (46)
  Classroom lessons, n (%)   10 (42)
  Physical activity lessons, n (%)   5 (21)
  Incentive scheme, n (%)   4 (17)
  Change in school/classroom environment, n (%)   4 (17)
  Peer support, n (%)   3 (13)
  Support for parents/guardians, n (%)   3 (13)
  Goal setting, n (%)   2 (8)
  Staff training, n (%)   2 (8)
  Home activities, n (%)   2 (8)
  Extracurricular physical activity, n (%)   2 (8)
  Parent’s evenings, n (%)   1 (4)
  Drama workshops, n (%)   1 (4)
  Funding, n (%)   1 (4)
  School action group formation, n (%)   1 (4)
  School club sessions, n (%)   1 (4)
  Screening, n (%)   1 (4)
  Feedback, n (%)   1 (4)
  Motivational interviews, n (%)   1 (4)
  Interactive sessions, n (%)   1 (4)
  Discussions with parents/guardians, n (%)   1 (4)
  Gamification (competitive) techniques, n (%)   1 (4)
Type of control group 24  
  Usual care, n (%)   21 (88)
  Active, n (%)   2 (8)
  Two control groups (one usual care and one active control), n (%)   1 (4)
Study design
Justification for CRT design 24  
  Yes, n (%)   5 (21)
Type of randomisation 24  
  Completely randomised, n (%)   11 (46)
  Minimisation, n (%)   5 (21)
  Stratified, n (%)   4 (17)
  Matched pair, n (%)   3 (13)
  Constrained [52, 53], n (%)   1 (4)
Number of trial conditions 24  
  Two, n (%)   21 (88)
  Three, n (%)   2 (8)
  Four, n (%)   1 (4)
Length of follow-up 24  
  Up to 6 months, n (%)   11 (46)
  7 to 12 months, n (%)   8 (33)
  13 to 18 months, n (%)   3 (13)
  More than 18 months, n (%)   1 (4)
  Not stated, n (%)   1 (4)
Were pupils recruited before randomisation of clusters? 24  
  Pupils recruited before randomisation, n (%)   12 (50)
  Pupils recruited after randomisation, n (%)   4 (17)
  Unclear, n (%)   8 (33)
Were baseline cluster-level characteristics reported? 24  
  Yes, n (%)   13 (54)
Ethical approval
Was ethical approval obtained? 24  
  Yes, n (%)   22 (92)
  No, n (%)   1 (4)
  Not stated, n (%)   1 (4)
Sample size
Type of justification for sample size 24  
  Formal sample size calculationd, n (%)   3 (13)
  Other justification, n (%)   19 (79)
  Not stated, n (%)   2 (8)
Target number of schools, median (IQR; range) 18 7.5 (5 to 8; 2 to 20)
Target number of clusters, median (IQR; range) 18 7.5 (5 to 8; 2 to 20)
Target number of pupils, median (IQR; range) 13 320 (150 to 1200; 50 to 1852)
Achieved number of schools, median (IQR; range) 24 7.5 (4.5 to 9; 2 to 37)
Achieved number of clusters, median (IQR; range) 24 8 (5.5 to 9.5; 2 to 37)
Achieved number of pupils, median (IQR; range) 24 274 (179 to 557; 29 to 1567)
Achieved mean cluster size, median (IQR; range) 24 35.9 (24 to 89.4; 1.4 to 237.7)
Objectives of the feasibility study
Feasibility objectives 24  
  Test randomisation process, n (%)   3 (13)
  Test data collection process, n (%)   8 (33)
  Test willingness to be randomised (at cluster level and/or individual levels), n (%)   4 (17)
  Estimate recruitment percentage (at cluster level and/or individual levels), n (%)   15 (63)
  Estimate follow-up percentage (at cluster level and/or individual levels), n (%)   15 (63)
  Test implementation of intervention, n (%)   10 (42)
  Test compliance with intervention, n (%)   6 (25)
  Assess acceptability of intervention (at cluster level and/or individual levels), n (%)   16 (67)
  Assess acceptability of trial procedures (at cluster level and/or individual levels), n (%)   6 (25)
  Test the feasibility of blinding procedures, n (%)   0 (0)
  Test outcome measures, n (%)   14 (58)
  Estimate standard deviation of continuous outcomes or control arm rate for binary outcomes, n (%)   1 (4)
  Test consent procedures, n (%)   0 (0)
  Identify potential harms, n (%)   3 (13)
  Assess potential effectiveness of intervention, n (%)   17 (71)
  Estimate intervention cost, n (%)   7 (29)
  Estimate the ICC of the primary outcome, n (%)   2 (8)
  Estimate sample size for definitive trial, n (%)   5 (21)
Other study characteristics of methodological interest
Analysis method for estimating potential effectiveness 24  
  Individual-level analysis that allows for clustering, n (%)   9 (38)
  Cluster-level analysis, n (%)   4 (17)
  Did not account for clustering, n (%)   4 (17)
  Not stated, n (%)   3 (13)
  Did not estimate potential effectiveness, n (%)   4 (17)
P-value reported for effectiveness 24  
 Yes, n (%)   8 (33)
  1. aSome studies included more than one school type. This is the number of studies that included specific types of school. State schools receive funding through their local authority or directly from the government. The most common ones are local authority, foundation and voluntary aided school which are all funded by the local authority. Academies are run by government and not-for-profit trusts, and are independent of local authority. Grammar schools are run by local authorities but intake is based on assessment of the pupils’ academic ability. Special schools cater for pupils with special educational needs. Faith schools follow the national curriculum but can decide what they teach in religious studies. Independent schools follow the national curriculum but charge fees for attending pupils
  2. bIntervention type has been described using the typology of Eldridge and Kerry [1]. ‘Individual-cluster’ interventions contain components that are aimed at the individual level (e.g., goal setting). ‘Professional-cluster’ interventions contain components that are delivered by a professional or person internal to the cluster (e.g., teacher, pupils). ‘External-cluster’ interventions contain components that require people external to the cluster to deliver the intervention (e.g., research staff, community support consultant). ‘Cluster–cluster’ interventions contain components that have to be delivered at the cluster level (e.g., classroom lessons). ‘Multifaceted’ interventions contain components across more than one of the ‘individual-cluster’, ‘professional-cluster’, ‘external-cluster’ and ‘cluster–cluster’ categories
  3. cExamples of each intervention component are provided for ease of understanding. Resources and materials (e.g., a resource box comprising food models, food mats, food cards, DVDs, and books); Classroom lessons (e.g., interactive film-based sexual-health lesson); Physical activity lessons (e.g., active play sessions, brisk walking programme during the school day); Incentive schemes (e.g., lottery-based incentive scheme to promote active travel to school); Peer support (e.g., informal peer-led smoking prevention); Change in school/classroom environment (e.g., sit-stand desks to replace standard desks, challenging attitudes and perceived norms concerning gender stereotypes and dating and relationship violence); Support for parents/guardians (e.g., information sheets about health eating habits); Goal setting (e.g., goal setting to engage and support schools); Staff training (e.g., staff training in restorative school action group formation); Home activities (e.g., home activities that encourage pupils to be more active, eat more nutritious foods, and spend less time in screen-based activities); Extracurricular physical activity (e.g., staff delivered after-school physical activity programme); Drama workshops (e.g., interactive drama workshops); School action group formation (e.g., to address bullying and aggression within schools); School club sessions (e.g., health eating club); Screening (e.g., alcohol screening and brief intervention to reduce hazardous drinking in younger adolescents); Feedback (e.g., feedback about pupil’s drinking habits); Motivational interviews (e.g., motivational interviewing techniques to prevent alcohol misuse); Interactive sessions (e.g., interactive sessions with school learning mentors to prevent alcohol misuse); Discussions with parents/guardians (e.g., guided discussions conducted with parents); Gamification (competitive) techniques (e.g., gamification techniques to promote physical activity)
  4. dIn one study, the sample size was based on being able to estimate feasibility parameters with a pre-specified level of precision. Two studies based their sample size on a definitive test of intervention effectiveness