Impulsar a los emprendedores y fortalecer a las micro, pequeñas y

We found that STAMPP was effective in reducing self-reported HED T3, when pupils were aged

15–16 years. It will be important to assess whether or not these reductions are sustained and if effects on

harms emerge as pupils get older, alcohol use behaviours become more frequent and patterns of use are established.12,133,134_{Booster interventions (e.g. brief interventions of proven effectiveness in adolescents and}

young adults) that build upon the skills developed in STAMPP may prove useful in sustaining behavioural

change.135_{As the trial team included those who were responsible for the adaptation and development of}

the intervention, it is also important that any future replications are conducted independently.136_{The use}

of data linkage techniques to match the study cohort to additional educational, community and statutory

DISCUSSION

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service data sets (e.g. examination performance, hospital admissions, GP data, involvement with the criminal justice system) may also help to understand whether or not the changes reported in the current

study lead to meaningful changes in health and well-being outcomes.137_{This recommendation also applies}

to other alcohol prevention research that predominantly uses simple proxy outcomes of use,49_{and this}

practice has been criticised for not providing useful information for commissioners who are tasked with funding interventions on the basis of demonstrable improvements in health and well-being.

In an earlier secondary analysis assessing implementation of the adapted SHAHRP in NI,138_{multilevel growth}

modelling was used to examine differential intervention impact when recipients were retrospectively classed according to alcohol use status (abstainer or existing drinker) and context of use (unsupervised or parental/ carer supervised drinker) at baseline. Significant positive behavioural effects in terms of amounts consumed, frequency of drinking and self-reported alcohol-related harms were observed almost exclusively among pupils classed as baseline unsupervised drinkers. This was notable, as although the SHAHRP was delivered as a universal curriculum, it suggested that it might also have utility as a targeted intervention. In the current study, the preplanned subgroup analysis showed that there was no interaction between baseline drinking status and treatment effect. However, when exploratory analyses were undertaken, which examined drinking status groups independently, significant intervention effects emerged (HED and self-reported harms). These findings suggest that STAMPP may have had a differential impact on those pupils who would

be considered most at risk from alcohol use (e.g. unsupervised baseline drinkers).139

With respect to further development of STAMPP intervention, our rich data set means that it will be possible to conduct mediation analysis to further develop programme theory and to test the assumptions of our logic model (see Appendix 1). This may lead to a better understanding of which components of the

intervention (e.g. specific lessons) were most successful and which require strengthening.140_Identifying

supportive or inert elements of the programme may lead to the development of a shorter optimised curriculum, which would reduce resource requirements and potentially increase the attractiveness of the intervention to funders. Similarly, analysis of moderation effects might identify local contextual and

population factors that exert differential influences on outcomes.141

Extending this line of work, research examining the fidelity of implementation in more detail may help to refine delivery. Although we reported relatively high completeness of delivery with respect to content, there was variation in the number of lessons required to deliver, and it is uncertain what effect this may have had on programme outcomes. In a secondary analysis of the European Drug Addiction Prevention (EU-Dap) trial substance use prevention curriculum, another skills-based interactive prevention programme, class size, composition (e.g. sex ratio, academic ability) and social connectedness between pupils, were

shown to be important predictors of programme implementation.114_{Understanding these factors is}

important, because in routine practice, outside of the structures of a RCT, the intervention may not be delivered as intended, and formal and informal changes introduced by delivery staff may lead to a loss of

programme integrity.90_{Furthermore, although based in the classroom, the adapted SHAHRP curriculum}

may not necessarily be optimally delivered by teachers,60_{and some pupils in the process evaluation}

suggested that their response to the lessons was dependent on pre-existing relationships with school staff. In future programme development and evaluation, different trial arms should include the assessment of alternative deliverers, such as trained prevention and youth service workers, who have specialist skills to help better engage young people in health programmes.

Considering our failure to recruit into the parental intervention, further research is required to better

understand how to engage and retain parents/carers in prevention activities.91,123_{This is also important,}

as delivery of preventative activities outside of the structures of research trials frequently leads to lower

implementation quality.90_{Universal interventions such as STAMPP require a range of recruitment strategies,}

as there will be different barriers to, and facilitators of, attendance in parental/carer-based actions. Research is therefore needed to assess the relative efficacy of recruitment strategies such as incentives, mass media campaigns, the removal of barriers to attendance (e.g. providing transport and childcare) and

important to understand if some parent/carer subgroups (e.g. differentiated according to child drinking risk) are more likely to respond to particular recruitment strategies and if this will lead to recruitment biases. Broadening our research recommendations to the wider prevention field, and drawing upon our stakeholder interviews, it is clear that although universal interventions are valued, they compete for resources and must sit alongside other alcohol-related community actions and policy initiatives, which

may moderate observed effects.92_{By-laws and licensing decisions can affect local alcohol environments}

(e.g. density of alcohol outlets, opening hours and local marketing), and actions such as industry-driven corporate social responsibility initiatives, marketing and packaging regulations and community-based

initiatives may complement or disrupt school-based actions.93–97There is also increasing interest in schools

as environments for health promotion through actions that modify the physical and social environment.98

Interventions and curricula, such as STAMPP, are therefore not being delivered in isolation, and, although study design characteristics such as randomisation control for internal biases, there is a need to better understand how interventions complement each other, the dynamic interplay between intervention components at different levels (e.g. the interaction between norms correction activities in a prevention curriculum and the placement of alcohol advertisements in the local area), and how interventions can be

optimised within such complex health systems.99_{The use of systems mapping exercises and the study of}

alcohol prevention as a complex system may be one means to maximise effects from combinations of different prevention types.100