The Happy Healthy Active Children (HHAC) initiative is a multicomponent community-based initiative aimed at promoting physical activity, food literacy and nature literacy among children in early childhood kindergarten and primary school settings. Developed in collaboration between Activity Experts and Community Stakeholders, HHAC integrates thematic activities (Play, Nature, Food) across kindergartens, schools and the broader community. The initiative responds to growing concerns about declining physical activity levels, insufficient contact with nature and poor dietary habits in childhood, factors known to influence long-term health and well-being. This protocol outlines the design, implementation and planned evaluation of the HHAC initiative.

HHAC is carried out within the long-term strategic initiative Tingbjerg Changing Diabetes. Following the Supersetting approach, HHAC addresses inequity in health by mobilising resources across local settings (kindergartens, schools and the local community arenas) and population groups (children, parents, staff and other community members) to develop and implement contextually relevant activities promoting outdoor play, cooking and nature experiences. Activities are evaluated using a within-subject design in kindergartens, while in schools a quasi-experimental design with matched control groups is applied. Data is collected at baseline and follow-up through accelerometry, validated questionnaires and structured observations. Primary outcomes include physical activity levels, food literacy and nature literacy. Analyses apply linear mixed-effects models to account for repeated measures and clustering at the institutional level. The evaluation also investigates implementation processes and context-mechanism configurations through a comprehensive realist evaluation. This includes developing a programme theory, conducting interviews with children, parents, staff and other local stakeholders and participant observations aiming to explore experiences and the mechanisms through which the activities contribute to changes in behaviour and well-being. All data will be analysed and condensed for a model for transferability.

Findings will be disseminated through peer-reviewed journals, conference presentations and public engagement activities targeting educators, policymakers and health professionals. The intervention materials will also be made freely available to support broader implementation. The study procedures were registered and approved by The Capital Region’s centre for data reviews ‘Videnscenter for Dataanmeldelser’ (Reference: P-2023–14277). All procedures were carried out under relevant regulations and guidelines. Written information about the study was given to all school principals, teachers and parents/guardians before the start of the study, and written informed consent is obtained from all legal guardians of all participants in their native language prior to child enrolment.

To develop prediction models for short-term outcomes following a first acute myocardial infarction (AMI) event (index) or for past AMI events (prevalent) in a national primary care cohort.

Retrospective cohort study using logistic regression models to estimate 1-year and 5-year risks of all-cause mortality and composite cardiovascular outcomes.

Primary care practices in England contributing data to the Clinical Practice Research Datalink (CPRD) Aurum and CPRD GOLD databases between 2006 and 2019.

Patients with an incident (index) or prevalent AMI event. Models were trained on a random 80% sample of CPRD Aurum (n=1018 practices), internally validated on the remaining 20% (n=255) and externally validated using CPRD GOLD (n=248).

Discrimination assessed using sensitivity, specificity and area under the receiver operating characteristic curve (AUC). Calibration assessed using calibration plots.

In the index (prevalent) cohorts, 94 241 (64 789) patients were included in the training and internal validation sets, and 16 832 (7479) in the external validation set. For the index cohort, AUCs for 1-year [5-year] all-cause mortality were 0.802 (95% CI 0.793 to 0.812) [0.847 (0.841 to 0.853)] internally and 0.800 (0.790 to 0.810) [0.841 (0.835 to 0.847)] externally. For the primary composite outcome (stroke, heart failure and all-cause death), AUCs were 0.763 (0.756 to 0.771) [0.824 (0.818 to 0.830)] internally and 0.748 (0.739 to 0.756) [0.808 (0.801 to 0.815)] externally. Discrimination was higher in the prevalent cohort, particularly for 1-year mortality (AUC: 0.896, 95% CI 0.887 to 0.904). Models excluding treatment variables showed slightly lower but comparable performance. Calibration was acceptable across models.

These models can support clinicians in identifying patients at increased risk of short-term adverse outcomes following AMI, whether newly diagnosed or with a prior history. This can inform monitoring strategies and secondary prevention and guide patient counselling on modifiable risk factors.