Introduction: While public trust is often cited as a key factor influencing rates of deceased organ donation, empirical research validating this assumption remains limited. In response to this gap, a conceptual model was developed (Martínez-López et al., 2023) to systematically examine trust relationships in organ donation and transplantation (ODT). This model identifies key trustors (e.g., potential donors, families, recipients, healthcare professionals), trustees (including institutions and society), and culturally relevant objects of trust (e.g., autonomy, usefulness, respectful treatment, and fairness). Building on this model, the present study aims to develop and validate a scale for measuring public trust in ODT systems and to explore how trust dynamics influence willingness to donate and family decision-making across populations.
Method: Following the scale development framework proposed by Boateng et al. (2018), the study was conducted in three phases. During Phase 1, the research team conceptualized the dimensions of interest and developed the items to measure them. An expert panel was sought to evaluate these proposals using the Delphi methodology. In Phase 2, the scale was pre-tested by administering the questionnaire to participants as a pilot study. This stage also served to extract factors and establish sample sizes that ensured sufficient statistical power. Phase 3 involves conducting several tests to assess dimensionality, reliability, and validity.
Results: Preliminary results from Phases 1 and 2 include a proposed questionnaire aligned with the trust model. The instrument incorporates items targeting various trust relationships and perceived attributes across different actors in the ODT system. The pilot study results will be presented at the conference, including item structure and feedback gathered to guide further scale refinement.
Conclusion: The development of a validated ODT trust scale represents a novel step toward empirically assessing the role of trust in organ donation systems. By operationalizing trust relationships across societal and institutional levels, this tool can inform future cross-cultural research and policy strategies aimed at improving organ donation rates and public engagement.

References
Boateng, G. O., Neilands, T. B., Frongillo, E. A., R., H., & Young, S. L. (2018). Best Practices for Developing and Validating Scales for Health, Social, and Behavioral Research: A Primer. Frontiers in Public Health, 6, 366616. https://doi.org/10.3389/fpubh.2018.00149.
Martínez-López, M.V., McLaughlin, L., Molina-Pérez, A. et al. Mapping trust relationships in organ donation and transplantation: a conceptual model. BMC Med Ethics 24, 93 (2023). https://doi.org/10.1186/s12910-023-00965-2.