Do summaries of evidence enable informed decision-making about COVID-19 and influenza vaccination equitably across more and less disadvantaged groups? Study protocol for a multi-centre cluster randomised controlled trial of 'fact boxes in health and social care in Germany

Introduction
Evidence summaries on the benefits and harms of treatment options support informed decisions under controlled conditions. However, few studies have investigated how such formats support decision-making across different social groups. There is a risk that only disadvantaged people will be able to make informed health decisions—possibly increasing the health equity gap. It is also unclear whether they support decision-making in the field at all. The aim of our study is to assess whether evidence summaries based on the fact box format can help people from different social groups make informed decisions about COVID-19 and influenza vaccinations, and thus reduce inequity in health communication.

Methods and analysis
In a multi-centre, cluster-randomised, controlled trial, health educators from usual care and outreach work in Germany will be randomised in a 1:1 ratio to provide either usual health communication plus an evidence summary (‘fact box’) or usual health communication. Health educators provide a flyer about COVID-19 or influenza vaccination which contains a link to an online study either with (intervention) or without (control) fact box on the reverse side. Flyer and online study will be available in Arabic, German, Turkish and Russian language. The primary outcome is informed vaccination intention, based on vaccination knowledge, attitudes, intentions and behaviour. Secondary outcomes include risk perception, decisional conflict and shared decision-making. We will use linear mixed models to analyse the influence of both individual (eg, education status) and cluster level factors and account for the expected cluster variability in realising usual health communication or the intervention. The statistical analysis plan includes the selection of appropriate measures of effect size and power calculation, assuming a sample size of 800 patients.

Ethics and dissemination
The trial has been approved by the Ethics Committee of the University of Potsdam, Germany (application numbers: 34/2021 and 57/2022).
Results will be disseminated through peer-reviewed journals, conferences and to relevant stakeholders.

Protocol version
Version 6 (4 October 2024); Preprint available on Research Square: https://doi.org/10.21203/rs.3.rs-3401234/v3

Trial registration number
NCT06076421.

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Novembre 2024

Effect of calcium channel blockers on influenza incidence: a population-based retrospective cohort study using administrative claims data in Japan

Objectives
Laboratory experiments have indicated that calcium channel blockers (CCBs) inhibit the entry and replication of influenza A virus in cells. However, no clinical studies have assessed the incidence of influenza among patients receiving CCBs. This study aimed to investigate the association between CCB use and the incidence of influenza among patients with hypertension using administrative claims data in Japan.

Design
Retrospective cohort study.

Setting
Administrative health insurance claims database of Kumamoto Prefecture, Japan.

Participants
360 515 patients with hypertension (10th edition of the International Classification of Diseases code I10) who were prescribed CCBs and 171 142 patients who were prescribed angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs) between 2012 and 2016.

Primary outcome
We compared the incidence of influenza between the CCB and ACEI/ARB groups using high-dimensional propensity-score (HD-PS) matching.

Results
A total of 166 814 HD-PS matched pairs were obtained. Before HD-PS matching, the CCB group had a significantly lower influenza incidence than the ACEI/ARB group in the overall analysis (2.4% vs 2.5%, p=0.007; risk ratio 0.95, 95% CI 0.92 to 0.99). However, no significant difference was observed between the two groups after HD-PS matching (2.4% vs 2.5%, p=0.067; risk ratio 0.96, 95% CI 0.92 to 1.00); only in 2012 did the CCB group have a significantly lower likelihood of influenza than the ACEI/ARB group.

Conclusions
No significant difference was observed in the influenza incidence between the CCB and ACEI/ARB groups. A direct comparative study between background-matched patients with and without CCBs is warranted to confirm the effect of CCBs on reducing the incidence of influenza.

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Ottobre 2024