Background: Core outcome sets (COSs) bring consistency to outcome measurement and strengthen systematic reviews. Most COSs focus on clinical interventions for health conditions; few address preventive health interventions.Communication for childhood vaccination is key to improving uptake and can take many forms. Measurement requires appropriate outcomes, but it is not clear what these outcomes should be or how COS methods apply to this context. Here we describe novel methods for developing a Trial Outcomes Map (TOM), a helpful tool for the early stages of COS development. Objectives: To catalogue which outcomes have been measured in childhood vaccination communication trials and describe (in)consistencies and patterns in these with a TOM. Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) for relevant trials and extracted outcome details. Outcomes were inductively coded into thematic groups, forming the map. Consistencies, gaps and trends were analysed. Results: We extracted data on 209 outcomes from 112 trials. We found variation and gaps in reported outcomes.Thematic grouping identified three overarching categories: vaccination-, consumer- and health system-related outcomes. Vaccination-related outcomes were reported most frequently: 80% of trials measured at least one such outcome, although these outcomes were defined and measured in a wide range of ways. Consumer-related outcomes, tied mainly to knowledge, attitudes or beliefs, were measured by 28% of trials. Health system-related outcomes were measured in 20% of trials. Trials published after 2000 appeared to include more consumer-related outcomes, possibly reflecting increased interest in shared decision making.Conclusions: This map highlights variation in the measurement of key vaccination outcomes, leading to difficulties in interpretation and synthesis. A trend towards more consumer-related outcomes emerges, but intermediate consumer- and health system-related outcomes that clarify vaccination communication causal pathways are not measured sufficiently frequently in trials. This map is a tool for trialists and reviewers and will inform the next stages of COS development.
A map of outcomes in trials of communication interventions for childhood vaccination: measuring too few concepts in too many ways
1Centre for Health Communication and Participation, La Trobe University, Australia, 2Swiss Tropical and Public Health Institute, University of Basel, Switzerland, 3International Union for Health Promotion and Education, France, 4Universidade Eduardo Mondlane, Mozambique, 5Global Health Unit, Norwegian Knowledge Centre for the Health Services, Norway, 6Global Health Unit, Norwegian Knowledge Centre for the Health Services, Norway/Health Systems Research Unit, South African Medical Research Council, South Africa, 7Catholic University of Chile, Chile, 8Provincial Directorate of Health, Mozambique, 9University of Calabar, Nigeria