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

Table 3 Cluster-level characteristics used to balance the randomisation (N = 64)

Characteristic	Statistic
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 – Unspecified^d, 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)
Other^e
Yes, n (%)	24 (38)

^aTownsend Index quantifies material deprivation within a population
^bIncome Deprivation Affecting Children Index (IDACI) is the proportion of all children aged 0 to 15 living in income deprived families in different local areas across England
^cIndex of Multiple Deprivation (IMD) measures relative deprivation for small areas (or neighbourhoods) in England
^dDid not state which measure of deprivation used
^eOther balancing factors include: Percentage of students who actively commuted to school; School; English-speaking versus Welsh-speaking school; Local sexual health services; Number of students in year group; Date of entry of school into study; School in urban versus rural area; Percentage of children speaking English as an additional language; Quality and quantity of current school sex education; Local authority; Percentage of pupils staying on after age 16 years; Special educational need status; Whether school has existing policy similar to the intervention; School expressed preference for allocation (control versus intervention versus no preference); Health-promoting school status; Percentage of children in year group of interest with no dental decay; Frequency and timetabling of personal, social, and health education lessons; Preferred timetabling of the intervention; Facilitator of the intervention (Regional Project Manager)

ISSN: 1471-2288