Theory-based design and field-testing of an intervention to support women choosing surgery for breast cancer: BresDex

Objective: Design and undertake usability and field-testing evaluation of a theory-guided decision aid (BresDex) in supporting women choosing surgery for early breast cancer. Methods: An extended Theory of Planned Behavior (TPB) and the Common Sense Model of Illness Representations (CSM) guided the design of BresDex. BresDex was evaluated and refined across 3 cycles by interviewing 6 women without personal history of breast cancer, 8 women with personal history of breast cancer who had completed treatment and 11 women newly diagnosed with breast cancer. Participants were interviewed for views on content, presentation (usability) and perceived usefulness towards deciding on treatment (utility). Framework analysis was used, guided by the extended TPB and the CSM. Results: BresDex was positively received in content and presentation (usability). It appeared an effective support to decision-making and useful source for further information, particularly in clarifying attitudes, social norms and perceived behavioral control, and presenting consequences of decisions (utility). Conclusion: This study illustrates the potential benefit of the extended TPB and CSM in designing a decision aid to support women choosing breast cancer surgery. Practice implications: BresDex could provide decision-making support and serve as an additional source of information, to complement the care received from the clinical team.