Decision support training for advanced cancer family caregivers: Study protocol for the CASCADE factorial trial

Background: Patients with advanced cancer face numerous decisions when diagnosed and often receive decision support from family caregivers. The CASCADE (CAre Supporters Coached to be Adept DEcision partners) factorial trial intervention aims to train caregivers in skills to provide effective decision support to patients and identify most effective intervention components. Methods: This is a 2-site, single-blind, 2⁴ factorial trial to test components of the CASCADE decision support training intervention for family caregivers of patients with newly-diagnosed advanced cancer delivered by specially-trained, telehealth, palliative care lay coaches over 24 weeks. Family caregivers (target N = 352) are randomly assigned to one of 16 combinations of four components with two levels each: 1) psychoeducation on effective decision partnering principles (1 vs. 3 sessions); 2) decision support communication training (1 session vs. none); 3) Ottawa Decision Guide training (1 session vs. none) and 4) monthly follow-up (1 call vs. calls for 24 weeks). The primary outcome is patient-reported decisional conflict at 24 weeks. Secondary outcomes include patient distress, healthcare utilization, caregiver distress, and quality of life. Mediators and moderators (e.g., sociodemographics, decision self-efficacy, social support) will be explored between intervention components and outcomes. Results will be used to build two versions of CASCADE: one with only effective components (d ≥ 0.30) and another optimized for scalability and cost. Discussion: This protocol describes the first factorial trial, informed by the multiphase optimization strategy, of a palliative care decision-support intervention for advanced cancer family caregivers and will address the field's need to identify effective components that support serious illness decision-making.