Development and validation of the Therapy Preference Scale to understand patients´ systemic cancer treatment preferences.

We incorporated questions related to safety, effectiveness and other characteristics of systemic cancer treatment into a self-report questionnaire - the Therapy Preference Scale - that captures patients´ preferences. The authors asked 20 experts to assess content validity and an additional 20 experts, patients and community members to examine face validity and guide revisions. Key revisions included shortening the length, clarifying constructs and providing details to explain the context and trade-offs necessary to balance the risks and benefits of cancer treatment. The content validity index for the final questionnaire was 1.0, indicating that all questions were relevant. Reviewers expressed that the questionnaire would serve an important purpose. Experts, patients and community members guided revisions of the questionnaire and documented its value.