Background
Methods
Data sources and search methods
Search strategy |
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Terms for randomised controlled trials: |
1. random:.mp. |
2. trial.ab, kw, ti. |
Cluster design-related terms: |
3. “cluster*”.ab, kw, ti. |
4. “group*”.ab, kw, ti. |
5. “communit*”.ab, kw, ti. |
6. 3 OR 4 OR 5 |
School MeSH term: |
7. exp Schools/ |
Highest precision: |
8. 1 AND 2 AND 6 AND 7 |
9. 8 limited to English language |
Inclusion and exclusion criteria
Sifting and validation
Data extraction and analysis
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Publication details: year of publication and journal name.
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Setting characteristics: country/region, school level and type of school.
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Intervention: health area and intervention type.
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Primary outcome: name, health area, reporter of outcome and method of data collection.
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Study design and analysis methods: unit of randomisation (i.e., type of cluster), justification for using the cluster trial design, method used to sample schools, method used to balance the randomisation, length and number of follow-ups, design of follow-up (cohort versus repeated cross-sectional design) and method used to account for clustering in the analysis.
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Sample size calculation: target sample size (i.e., number of clusters and pupils) and assumptions underlying the sample size calculation (e.g., assumed ICC, percentage loss to follow-up).
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Ethics and consent procedures: activities covered by the consent agreements and use of “opt-out” consent.
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Other study characteristics of methodological interest: number of clusters and pupils that were recruited and lost to follow-up, estimate of the ICC of the primary outcome.
Results
Search results
Study characteristics
Characteristic | N | Statistics |
---|---|---|
Setting | ||
Country | 64 | |
England, n (%) | 47 (73) | |
Scotland, n (%) | 5 (8) | |
Wales, n (%) | 3 (5) | |
Northern Ireland, n (%) | 3 (5) | |
More than one countrya, n (%) | 6 (9) | |
Number of regions from which schools were drawnb | 64 | |
One | 40 (62) | |
Two | 10 (16) | |
Three | 1 (2) | |
Four | 1 (2) | |
Unclear | 12 (19) | |
School level | 64 | |
Preschool only, n (%) | 2 (3) | |
Primary only, n (%) | 36 (56) | |
Secondary only, n (%) | 24 (38) | |
Primary and Secondary, n (%) | 2 (3) | |
School types that were included [83]c | 44 | |
State, n (%) | 41 (93) | |
Independent, n (%) | 6 (14) | |
Academies, n (%) | 2 (5) | |
Grammar, n (%) | 2 (5) | |
Special, n (%) | 2 (5) | |
Voluntary aided, n (%) | 2 (5) | |
Foundation, n (%) | 1 (2) | |
Faith, n (%) | 1 (2) | |
Intervention | ||
Health area of interventiond | 64 | |
Nutrition, n (%) | 18 (28) | |
Physical activity, n (%) | 15 (23) | |
Socioemotional function and its influencese, n (%) | 15 (23) | |
Dental health, n (%) | 7 (11) | |
Smoking, n (%) | 5 (8) | |
Injury, n (%) | 5 (8) | |
Sexual health, n (%) | 3 (5) | |
Alcohol misuse, n (%) | 2 (3) | |
Cancer, n (%) | 1 (2) | |
Communication skills (for children with autism), n (%) | 1 (2) | |
Health attitudes (breast feeding), n (%) | 1 (2) | |
Level of prevention | 64 | |
Primary prevention, n (%) | 60 (94) | |
Secondary prevention, n (%) | 4 (6) | |
Type of intervention [1]f | 64 | |
Individual-cluster, n (%) | 11 (17) | |
Professional-cluster, n (%) | 33 (52) | |
External-cluster, n (%) | 32 (50) | |
Cluster–cluster, n (%) | 53 (83) | |
Multifaceted, n (%) | 53 (83) | |
Primary outcome | ||
Primary outcome health area | 64 | |
Socioemotional function and its influencesg, n (%) | 15 (23) | |
Nutrition, n (%) | 10 (16) | |
Dental health, n (%) | 7 (11) | |
Physical activity, n (%) | 7 (11) | |
Obesity, n (%) | 7 (11) | |
Smoking, n (%) | 5 (8) | |
Injury, n (%) | 3 (5) | |
Sexual health, n (%) | 2 (3) | |
Obstetrics, n (%) | 2 (3) | |
Alcohol misuse, n (%) | 2 (3) | |
Cancer, n (%) | 1 (2) | |
Communication skills (for children with autism), n (%) | 1 (2) | |
Gross motor skills, n (%) | 1 (2) | |
Safety, n (%) | 1 (2) | |
Main reporter of primary outcome | 64 | |
Pupil, n (%) | 34 (53) | |
Researcher, n (%) | 12 (19) | |
Dentist, n (%) | 6 (9) | |
Teacher, n (%) | 5 (8) | |
Parent, n (%) | 4 (6) | |
Routine data, n (%) | 2 (3) | |
Researcher and parent, n (%) | 1 (2) | |
Primary outcome reporter blind to allocation status | 64 | |
Yes, n (%) | 18 (28) | |
No, n (%) | 46 (72) | |
Primary outcome measurement was objective | 64 | |
Yes, n (%) | 14 (22) | |
No, n (%) | 50 (78) | |
Study design and analysis methods | ||
Justification provided for randomising clusters | 64 | |
Yes, n (%) | 17 (27) | |
No, n (%) | 47 (73) | |
Reason for randomising clusters | 17 | |
To avoid contamination, n (%) | 9 (53) | |
Intervention was delivered at the cluster level, n (%) | 4 (24) | |
To avoid contamination and for logistical reasons, n (%) | 2 (12) | |
To avoid contamination and avoid “selection bias”, n (%) | 1 (6) | |
To avoid contamination and because intervention was delivered at the cluster level, n (%) | 1 (6) | |
Unit of randomisation | 64 | |
Schools, n (%) | 56 (88) | |
Classes, n (%) | 6 (9) | |
Year groups, n (%) | 2 (3) | |
Number of trial arms | 64 | |
Two, n (%) | 55 (86) | |
Three, n (%) | 5 (8) | |
Four, n (%) | 4 (6) | |
Study design | 64 | |
Parallel group, n (%) | 61 (95) | |
Factorial, n (%) | 3 (5) | |
Method used to sample schools | 64 | |
All potentially eligible schools invited, n (%) | 33 (52) | |
Random sample, n (%) | 5 (8) | |
Purposive sample, n (%) | 4 (6) | |
Convenience sample, n (%) | 3 (5) | |
Mixed random/convenience sample, n (%) | 1 (2) | |
Unclear, n (%) | 18 (28) | |
Type of randomisation | 64 | |
Completely randomised, n (%) | 13 (20) | |
Stratified, n (%) | 29 (45) | |
Matched, n (%) | 8 (13) | |
Minimisation, n (%) | 8 (13) | |
6 (9) | ||
Type of follow-up | 64 | |
Cohort, n (%) | 62 (97) | |
Repeated cross-sectional, n (%) | 1 (2) | |
Mixed, n (%) | 1 (2) | |
Number of follow-ups | 64 | |
1, n (%) | 32 (50) | |
2, n (%) | 21 (33) | |
3, n (%) | 6 (9) | |
4, n (%) | 5 (8) | |
Length of follow-up | 64 | |
Up to 6 months, n (%) | 22 (34) | |
7 to 12 months, n (%) | 19 (30) | |
13 to 18 months, n (%) | 6 (9) | |
19 to 24 months, n (%) | 8 (13) | |
25 to 36 months, n (%) | 7 (11) | |
More than 36 months, n (%) | 2 (3) | |
Participants recruited before clusters were randomised | 64 | |
Yes, n (%) | 21 (33) | |
No, n (%) | 17 (27) | |
Unclear, n (%) | 26 (41) | |
Baseline data collected before clusters were randomised | 64 | |
Yes, n (%) | 16 (25) | |
No, n (%) | 27 (42) | |
Unclear, n (%) | 21 (33) | |
Method of analysis | 64 | |
Individual-level analysis that allows for clustering, n (%) | 46 (72) | |
Cluster-level analysis, n (%) | 10 (16) | |
Did not allow for clustering, n (%) | 8 (12) | |
Sample size calculation | ||
Assumed school-level intra-cluster correlation coefficient of outcome, median (IQR; range) | 37 | 0.05 (0.02 to 0.1; 0.005 to 0.175) |
Assumed design effect, median (IQR; range) | 36 | 2.21 (1.98 to 3.53; 1.22 to 8.11) |
Study allowed for drop-out at cluster level | 64 | |
Yes, n (%) | 4 (6) | |
Not stated, n (%) | 60 (94) | |
Study allowed for drop-out at individual levelh | 62 | |
Yes, n (%) | 18 (29) | |
Not stated, n (%) | 44 (71) | |
Target number of clusters, median (IQR; range) | 46 | 30 (20 to 40; 4 to 160) |
Target number of schools, median (IQR; range) | 41 | 30 (20 to 42; 4 to 160) |
Target number of individuals, median (IQR; range)i | 45 | 964 (498 to 2000; 90 to 9000) |
Ethics and consent procedures | ||
From whom was consent/assent sought for pupil participation? | 64 | |
Parents and pupils, n (%) | 40 (63) | |
Parents only, n (%) | 15 (23) | |
Pupils only, n (%) | 2 (3) | |
Not stated / Neither parent nor pupil, n (%) | 7 (11) | |
Opt-out consent/assent procedure used for either parent/guardian or pupils | 64 | |
Yes, n (%) | 29 (45) | |
Not stated / No, n (%) | 35 (55) | |
Other study characteristics of methodological interest | ||
Ethnicity: percentage of pupils that are White, median (IQR; range) | 33 | 76.8 (51.5 to 86.2; 24 to 95.3) |
Total number of clusters recruited, median (IQR; range) | 62 | 31.5 (21 to 50; 4 to 486) |
Total number of schools recruited, median (IQR; range) | 63 | 29 (15 to 50; 4 to 486) |
Total number of pupils recruited, median (IQR; range)j | 60 | 1308 (604 to 3201; 17 to 27,435) |
Percentage of clusters followed-up for primary outcome, median (IQR; range) | 62 | 100 (92.5 to 100; 60.5 to 100) |
Percentage of pupils followed-up for primary outcome, median (IQR; range)k | 58 | 79.9 (64.1 to 87.5; 7.7 to 100) |
Observed school-level intra-cluster correlation coefficient of primary outcome, median (IQR; range) | 23 | 0.028 (0.017 to 0.12; 0.0005 to 0.21) |
Setting
Intervention type
Primary outcome
Study design and analysis methods
Characteristic | Statistic |
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Deprivation (school or area in which school is based) | |
Yes – Percentage of pupils eligible for free school meals, n (%) | 21 (33) |
Yes – Townsend Index [86]a, n (%) | 2 (3) |
Yes – Income Deprivation Affecting Children Index (IDACI) [87]b, n (%) | 1 (2) |
Yes – Index of Multiple Deprivation (IMD) [87]c, n (%) | 1 (2) |
Yes – Unspecifiedd, n (%) | 6 (9) |
Cluster size | |
Yes, n (%) | 23 (36) |
Geographic area of school | |
Yes, n (%) | 13 (20) |
Pupil ethnicity summary | |
Yes, n (%) | 5 (8) |
Co-educational status of school Yes, n (%) | 5 (8) |
School performance | |
Yes, n (%) | 5 (8) |
School type | |
Yes, n (%) | 2 (3) |
Othere | |
Yes, n (%) | 24 (38) |
Sample size calculation
Ethics and consent procedures
Other study characteristics of methodological interest
Author | Year | Cluster unit | Outcome | Health area | Outcome type | ICC estimate |
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Stallard [53] | 2012 | year group | Symptoms of low mood (depression) | socioemotional function | continuous | 0.012 |
Chisholm [22] | 2016 | class | Stigma of mental illness | socioemotional function | continuous | 0.1 |
Obsuth [71] | 2017 | school | School exclusion | socioemotional function | binary | 0.028 |
Connolly [82] | 2018 | school | Prosocial behaviour | socioemotional function | continuous | 0.116 |
Ford [32] | 2019 | school | Mental health / behaviour | socioemotional function | continuous | 0.121 |
Axford [44] | 2020 | school | Victimisation (being bullied) occurring at least twice a month in the last 2 months | socioemotional function | binary | 0.019 |
Campbell [26] | 2008 | school | Smoking in the past week | smoking | binary | 0.017 |
Conner [74] | 2019 | school | Ever smoking | smoking | binary | 0.017 |
McKay [24] | 2018 | school | Heavy episodic drinking in the previous 30 days (> = 6 units for males and > = 4.5 units for females) | alcohol misuse | binary | 0.121 |
Croker [40] | 2012 | school | Child's eating habits | obesity | continuous | 0.07 |
Fairclough [56] | 2013 | school | Waist circumference (cm) | obesity | continuous | 0.06 |
Lloyd [57] | 2018 | school | BMI z score | obesity | continuous | 0.014 |
Breheny [43] | 2020 | school | BMI z-score at 12 months | obesity | continuous | 0.001 |
Jago [41] | 2015 | school | Mean weekday minutes of moderate to vigorous physical activity per day | physical activity | continuous | 0.0005 |
Harrington [58] | 2018 | school | Minutes per day of moderate- to vigorous physical activity | physical activity | continuous | 0.02 |
Norris [67] | 2018 | school | Sedentary behaviour during the school day in minutes | physical activity | continuous | 0.080 |
Jamesa [28] | 2004 | class | Consumption of carbonated drinks over 3 days (in glasses) | nutrition | continuous | -0.009 |
Christian [25] | 2014 | school | Combined daily fruit and vegetable intake (grams per day) | nutrition | continuous | 0.003 |
Redmond [81] | 1999 | school | Proportion of teeth sites with caries at 6 months | dental health | continuous | 0.16 |
Worthington [31] | 2001 | school | Plaque score | dental health | continuous | 0.023 |
Milsom [59] | 2006 | school | Whether the child has active caries in their first permanent molars | dental health | binary | 0.027 |
Mulvaney [68] | 2006 | school | Use of visibility aid (reflective and fluorescent slap wrap) while cycling | injury | binary | 0.21 |
Kendrick [79] | 2007 | school | Knowledge score for fire and burn prevention | safety | continuous | 0.187 |
Hubbard [76] | 2016 | school | Number of recognised cancer warning signs | cancer | continuous | 0.038 |
Henderson [27] | 2007 | school | Terminations of pregnancy by age 20 | obstetrics | count | 0.005 |
Giles [23] | 2014 | school | Intention to breastfeed | obstetrics | continuous | 0.12 |