Intervention vignettes as a qualitative tool to refine complex intervention design

In trial design, decisions are made about which intervention components/processes to standardise and which remain flexible to maximise utility and/or effectiveness. The intervention-context-system fit for complex interventions impacts on trial recruitment, delivery and outcomes. Survey vignettes and discrete choice experiments are quantitative researcher led approaches which focus on a few measurable attributes. Our aim was to explore the utility of qualitative vignettes as a methodological tool allowing service users/providers to contribute to intervention design.

A case series of four acceptability and feasibility studies (qualitative interviews and focus groups) with service users and providers. Data were collected at different pre-trial stages: i) vignettes of studies in a systematic review of incentives for breastfeeding and smoking cessation in pregnancy, subsequently modified following emergent qualitative analysis; ii) emergent vignettes in the last of up to 8 serial qualitative interviews investigating infant feeding behaviour, following a systematic review showing poor generalizability of effective interventions in the UK context; iii) intervention vignettes of an effective intervention (groups for weight management) to refine the design for a new population (women treated for breast cancer) and iv) emergent intervention vignettes explored at a second interview with obese older adults.

Illustrations of how qualitative vignettes can complement quantitative design tools will be presented.

Carefully constructed qualitative vignettes combining known effective and emergent promising intervention aspects can optimise trial design. When talking service users and providers through a potential intervention, different perspectives emerge compared with responses to closed or more abstract questions.