Trial protocol and preliminary results for a cluster randomised trial of behavioural support versus brief advice for smoking cessation in adolescents

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.

Cigarette smoking and onset of mood and anxiety disorders

OBJECTIVES

We examined the association between regular cigarette smoking and new onset of mood and anxiety disorders.

METHODS

We used logistic regression analysis to detect associations between regular smoking and new-onset disorders during the 3-year follow-up among 34 653 participants in the longitudinal US National Epidemiologic Survey on Alcohol and Related Conditions (2001-2005). We used instrumental variable methods to assess the appropriateness of these models.

RESULTS

Regular smoking was associated with an increased risk of new onset of mood and anxiety disorders in multivariable analyses (Fdf = 5,61 = 11.73; P < .001). Participants who smoked a larger number of cigarettes daily displayed a trend toward greater likelihood of new-onset disorders. Age moderated the association of smoking with most new-onset disorders. The association was mostly statistically significant and generally stronger in participants aged 18 to 49 years but was smaller and mostly nonsignificant in older adults.

CONCLUSIONS

Our finding of a stronger association between regular cigarette smoking and increased risk of new-onset mood and anxiety disorders among younger adults suggest the need for vigorous antismoking campaigns and policy initiatives targeting this age group.