Objectives There is a need to inform the public about the risks as well as benefits of diagnostic and screening tests. This information should respond to pre-existing beliefs, concerns and needs, but we know relatively little about these. We examined Australian adults’ perceptions of diagnostic tests, testing risks, and the needs and concerns that lay people have when negotiating these risks.

Method We collected data using 12 semi-structured web-based focus groups with 62 Australian adults (aged 18+). We examined their attitudes to tests, testing risks, and practical factors influencing their testing choices. Two potential scenarios related to overtesting were used to explore these topics. Focus groups were video recorded. Transcripts were inductively coded using thematic analysis. Themes were mapped onto the COM-B framework of behaviour change in order to guide intervention design.

Results Thematic analysis suggested that participants largely saw themselves as self-efficacious, informed health consumers who already consider the risks and benefits of tests. They reported engaging in shared decision-making and asserting their preferences in clinical encounters. However, participants had a poor grasp of overtesting concepts, a narrow sense of testing risks, and largely did what doctors suggested. In clinical encounters, participants wanted to understand the logic behind testing decisions and maintain a locus of control. Personal testing experiences shaped the interpretation of overtesting issues. Structural factors affected their self-efficacy in negotiating testing choices. COM-B analysis showed that participants believed they faced few barriers to considering testing risks and were motivated and equipped to do so. In practice, participants’ possible overconfidence about their self-efficacy, limited acceptance of overtesting ideas, and barriers to engaging in shared decision-making during clinical encounters all inhibited them in avoiding overtesting in medical decision-making.

Conclusions We synthesised the thematic findings and COM-B analysis to identify solutions for patient-centred strategies to avoid overtesting. In this process, we also identified strategies that are unlikely to work. The final part of the talk will describe how our findings can be translated to public-facing resources that can help tackle the problem of overtesting.