A Practical Guide to Cluster Randomized Trials in School Health Research

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

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.

Dose-response associations between modifiable lifestyle behaviours and anxiety, depression and psychological distress symptoms in early adolescence

OBJECTIVE

To investigate associations between key modifiable lifestyle behaviours (sleep; physical activity; fruit, vegetable and sugar-sweetened beverage consumption; screen time; alcohol use and tobacco use) and mental health among early adolescents in Australia.

METHODS

Cross-sectional self-report data from 6,640 Year 7 students (M_age:12.7[0.5]; 50.6% male, 48.9% female, 0.5% non-binary) from 71 schools in New South Wales, Queensland and Western Australia were analysed using multivariate linear regression adjusting for sociodemographic factors and school-level clustering.

RESULTS

All examined behaviours were associated with anxiety, depression and psychological distress (p≤0.001), with the lowest mental health symptom scores observed in participants who slept 9.5-10.5 hours per night; consumed three serves of fruit daily; consumed two serves of vegetables daily; never or rarely drank sugar-sweetened beverages; engaged in six days of moderate-to-vigorous physical activity per week; kept daily recreational screen time to 31-60 minutes; had not consumed a full standard alcoholic drink (past six months); or smoked a cigarette (past six months).

CONCLUSIONS

Targeting modifiable risk behaviours offers promising prevention potential to improve adolescent mental health; however, further longitudinal research to determine directionality and behavioural interactions is needed.

IMPLICATIONS FOR PUBLIC HEALTH

While Australian Dietary, Movement and Alcohol Guidelines target physical health, findings indicate similar behaviour thresholds may offer mental health benefits.

The impact of antimicrobial resistance awareness interventions involving schoolchildren, development of an animation and parents engagements: a pilot study

Background

Antimicrobial resistance (AMR) is a global health challenge, particularly in low- and middle-income countries where antibiotics are widely available to consumers, leading to their misuse. However, AMR educational interventions for engaging parents of schoolchildren are mainly lacking in Sub-Saharan Africa. This study aimed to assess the potential of AMR animation and schoolchildren in influencing parents’ AMR knowledge, attitudes, and beliefs.

Methods

Parents of schoolchildren aged 11–15 years in Tema, a city in Ghana, watched and discussed an AMR animation designed with ideas from the schoolchildren’s top stories and picture drawings. The children from two schools were first engaged with AMR lessons, with one school using storytelling, the other school using picture drawing, and none serving as a control. The children were then asked to discuss the lessons with their parents. Baseline surveys of parents of randomly selected children were conducted to assess AMR knowledge, attitudes and beliefs before engaging the students and parents, and immediately after the parents participated in viewing and discussing the animation. McNemar and t-tests were used to assess changes in AMR knowledge, attitudes and beliefs.

Results

Parents who participated in the animation event, and whose schoolchildren were in the storytelling intervention school had significantly improved knowledge regarding the statement “Antibiotics will cure any infection” (p = 0.021, χ2 = 0.711; 88% vs 50%) between baseline and endline. However, these parents also had statistically significant decreased scores regarding the statement “Antibiotics do not kill our good bacteria” (p = 0.021, χ2 = 1.042; 71.4% vs 40%) between baseline and endline. There was no significant effect on any statement among parents whose children were in the picture drawing school. However, t-test results combining the statements as composite scores showed statistically significant difference in only the attitude construct among parents whose children participated in storytelling intervention (p = 0.043) or picture drawing intervention (p = 0.019). There were no statistically significant changes in knowledge and beliefs constructs.

Conclusions

This study shows that interventions involving schoolchildren with parents engagements and AMR animation could influence parents’ AMR attitudes. The intervention could also positively or negatively impact parents’ AMR knowledge. Modifications of the interventions may be needed for tackling AMR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01062-6.

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

Background

The last 20 years have seen a marked increase in the use of cluster randomised trials (CRTs) in schools to evaluate interventions for improving pupil health outcomes. Schools have limited resources and participating in full-scale trials can be challenging and costly, given their main purpose is education. Feasibility studies can be used to identify challenges with implementing interventions and delivering trials. This systematic review summarises methodological characteristics and objectives of school-based cluster randomised feasibility studies in the United Kingdom (UK).

Methods

We systematically searched MEDLINE from inception to 31 December 2020. Eligible papers were school-based feasibility CRTs that included health outcomes measured on pupils.

Results

Of 3285 articles identified, 24 were included. School-based feasibility CRTs have been increasingly used in the UK since the first publication in 2008. Five (21%) studies provided justification for the use of the CRT design. Three (13%) studies provided details of a formal sample size calculation, with only one of these allowing for clustering. The median (IQR; range) recruited sample size was 7.5 (4.5 to 9; 2 to 37) schools and 274 (179 to 557; 29 to 1567) pupils. The most common feasibility objectives were to estimate the potential effectiveness of the intervention (n = 17; 71%), assess acceptability of the intervention (n = 16; 67%), and estimate the recruitment/retention rates (n = 15; 63%). Only one study was used to assess whether cluster randomisation was appropriate, and none of the studies that randomised clusters before recruiting pupils assessed the possibility of recruitment bias. Besides potential effectiveness, cost-effectiveness, and the intra-cluster correlation coefficient, no studies quantified the precision of the feasibility parameter estimates.

Conclusions

Feasibility CRTs are increasingly used in schools prior to definitive trials of interventions for improving health in pupils. The average sample size of studies included in this review would be large enough to estimate pupil-level feasibility parameters (e.g., percentage followed up) with reasonable precision. The review highlights the need for clearer sample size justification and better reporting of the precision with which feasibility parameters are estimated. Better use could be made of feasibility CRTs to assess challenges that are specific to the cluster design.

Trial registration

PROSPERO: CRD42020218993.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-01098-w.

AVPCancerFree: Impact of a digital behavior change intervention on parental HPV vaccine -related perceptions and behaviors

Parent hesitancy contributes to reduced HPV vaccination rates. The HPVcancerfree app (HPVCF) was designed to assist parents in making evidence-based decisions regarding HPV vaccination. This study examined if parents of vaccine-eligible youth (11-12 yrs.) who use HPVCF in addition to usual care demonstrate significantly more positive intentions and attitudes toward HPV vaccination and greater HPV vaccination rates compared to those not using HPVCF. Clinics (n = 51) within a large urban pediatric network were randomly assigned to treatment (HPVCF + usual care) or comparison (usual care only) conditions in a RCT conducted between September 2017 and February 2019. Parents completed baseline and 5-month follow-up surveys. Participant-level analysis determined 1) change in HPV vaccination initiation behavior and related psychosocial determinants and 2) predictors of HPV vaccine initiation. Parents (n = 375) who completed baseline and 5-month follow-up surveys were female (95.2%), 40.8 (±5.8) yrs. married (83.7%), employed (68.3%), college educated (61.9%), and privately insured (76.5%). Between-group analysis of HPVCF efficacy demonstrated that parents assigned to receive HPVCF significantly increased knowledge about HPV and HPV vaccination (p < .05). Parents who accessed content within HPVCF significantly increased knowledge about HPV & HPV vaccine (p < .01) and perceived effectiveness of HPV vaccine (p < .05). Change in HPV vaccine initiation was not significant. A multivariate model to describe predictors of HPV vaccine initiation demonstrated an association with Tdap and MCV vaccination adoption, positive change in perceived effectiveness of the HPV vaccine, and reduction in perceived barriers against HPV vaccination. HPVCF appears to be a feasible adjunct to the education received in usual care visits and reinforces the value of apps to support the important persuasive voice of the health-care provider in overcoming parent HPV vaccine hesitancy.

Effect sizes and intra-cluster correlation coefficients measured from the Green Dot High School study for guiding sample size calculations when designing future violence prevention cluster randomized trials in school settings

Purpose

Cluster randomized controlled trials (cRCTs) are popular in school-based research designs where schools are randomized to different trial arms. To help guide future study planning, we provide information on anticipated effect sizes and intra-cluster correlation coefficients (ICCs), as well as school sizes, for dating violence (DV) and interpersonal violence outcomes based on data from a cRCT which evaluated the bystander-based violence intervention ‘Green Dot’.

Methods

We utilized data from 25 schools from the Green Dot High School study. Effect size and ICC values corresponding to dating and interpersonal violence outcomes are obtained from linear mixed effect models. We also calculated the required number of schools needed for future studies utilizing available methods that do and do not consider variation in school size.

Results

Observed effect sizes for DV outcomes range from 0.06 to 0.11. Observed ICC values for DV outcomes range from 0.0006 to 0.0032. The upper limit of 95% CIs for the true ICCs range from 0.0023 to 0.0070.

Conclusion

School-based evaluations with violence outcomes are expected to have small effect sizes. Observed ICCs are less than 0.005 and upper limit of of 95% CIs for the true ICCs are less than 0.01. Designing school-based cRCTs should account for the ICC, even if its value is assumed to be negligible. Furthermore, variation in school sizes should also be accounted for to avoid having too few schools to achieve the desired power.

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

Background

Cluster randomised trials (CRTs) are increasingly used to evaluate non-pharmacological interventions for improving child health. Although methodological challenges of CRTs are well documented, the characteristics of school-based CRTs with pupil health outcomes have not been systematically described. Our objective was to describe methodological characteristics of these studies in the United Kingdom (UK).

Methods

MEDLINE was systematically searched from inception to 30^th June 2020. Included studies used the CRT design in schools and measured primary outcomes on pupils. Study characteristics were described using descriptive statistics.

Results

Of 3138 articles identified, 64 were included. CRTs with pupil health outcomes have been increasingly used in the UK school setting since the earliest included paper was published in 1993; 37 (58%) studies were published after 2010. Of the 44 studies that reported information, 93% included state-funded schools. Thirty six (56%) were exclusively in primary schools and 24 (38%) exclusively in secondary schools. Schools were randomised in 56 studies, classrooms in 6 studies, and year groups in 2 studies. Eighty percent of studies used restricted randomisation to balance cluster-level characteristics between trial arms, but few provided justification for their choice of balancing factors. Interventions covered 11 different health areas; 53 (83%) included components that were necessarily administered to entire clusters. The median (interquartile range) number of clusters and pupils recruited was 31.5 (21 to 50) and 1308 (604 to 3201), respectively. In half the studies, at least one cluster dropped out. Only 26 (41%) studies reported the intra-cluster correlation coefficient (ICC) of the primary outcome from the analysis; this was often markedly different to the assumed ICC in the sample size calculation. The median (range) ICC for school clusters was 0.028 (0.0005 to 0.21).

Conclusions

The increasing pool of school-based CRTs examining pupil health outcomes provides methodological knowledge and highlights design challenges. Data from these studies should be used to identify the best school-level characteristics for balancing the randomisation. Better information on the ICC of pupil health outcomes is required to aid the planning of future CRTs. Improved reporting of the recruitment process will help to identify barriers to obtaining representative samples of schools.

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

INTRODUCTION

Cluster randomised trials (CRTs) are studies in which groups (clusters) of participants rather than the individuals themselves are randomised to trial arms. CRTs are becoming increasingly relevant for evaluating interventions delivered in school settings for improving the health of children. Schools are a convenient setting for health interventions targeted at children and the CRT design respects the clustered structure in schools (ie, pupils within classrooms/teachers within schools). Some of the methodological challenges of CRTs, such as ethical considerations for enrolment of children into trials and how best to handle the analysis of data from participants (pupils) that change clusters (schools), may be more salient for the school setting. A better understanding of the characteristics and methodological considerations of school-based CRTs of health interventions would inform the design of future similar studies. To our knowledge, this is the only systematic review to focus specifically on the characteristics and methodological practices of CRTs delivered in schools to evaluate interventions for improving health outcomes in pupils in the UK.

METHODS AND ANALYSIS

We will search for CRTs published from inception to 30 June 2020 inclusively indexed in MEDLINE (Ovid). We will identify relevant articles through title and abstract screening, and subsequent full-text screening for eligibility against predefined inclusion criteria. Disagreements will be resolved through discussion. Two independent reviewers will extract data for each study using a prepiloted data extraction form. Findings will be summarised using descriptive statistics and graphs.

ETHICS AND DISSEMINATION

This methodological systematic review does not require ethical approval as only secondary data extracted from papers will be analysed and the data are not linked to individual participants. After completion of the systematic review, the data will be analysed, and the findings disseminated through peer-reviewed publications and scientific meetings.

PROSPERO REGISTRATION NUMBER

CRD42020201792.