Development and validation of CORe-MBC: A measure of participatory care for adults with metastatic breast cancer.

377 Background: Greater patient participation in oncology care has been linked to enhanced patient-provider communication, improved symptom management, greater treatment adherence, and improved healthcare utilization among adults with cancer. While measures of patient engagement exist, few are tailored to the unique healthcare challenges and care decisions of patients with metastatic breast cancer (MBC); most also have limitations in terms of modality, cost, and potential for integration into oncology care. We sought to develop a measure of participatory care for MBC, referred to as the CORe-MBC (Capacity, Opportunity, and Resources in MBC), that would be easy for patients to complete as part of routine care. The purpose of the tool was to identify patients who have difficulty managing their care and to pinpoint the types of challenges encountered to help health systems better align limited resources. Methods: In consultation with MBC patients and oncologists, we conceptualized key components of participatory care, which included: 1) an individual’s capacity, or the knowledge and motivation needed to participate in MBC decision-making; 2) opportunity, or an inclusive healthcare environment with providers who listen to patients and seek to optimize MBC care in line with patient goals; and 3) resources, or the external factors that enable patients to manage their MBC. Candidate items for each domain were generated then refined following cognitive interviews with MBC patients. Resulting items were evaluated among English-speaking adults with MBC recruited from a large academic oncology center. Participants also completed structured surveys assessing health activation, self-efficacy, satisfaction with healthcare, and social support. Psychometric testing included exploratory factor analyses, using oblique rotations to evaluate factor structure, and parallel analysis to test for dimensionality. Results: A total of 130 patients were enrolled. Participants mostly identified as White (82%) and one-third (34%) had less than a college degree; the average age was 62.9 years (range 34-90). Candidate items loaded onto three factors (all factor loadings > .5), reflecting the domains of capacity, opportunity, and resources. A total of 10 items were selected for the final measure. Items demonstrated high internal consistency ( α = 0.83). Domains of capacity, opportunity, and resources demonstrated moderate to high construct validity with measures of health activation ( r = 0.56, p < 0.0001) and self-efficacy ( r = 0.31–0.40, p < 0.0005), satisfaction with healthcare ( r = 0.42–0.55, p < 0.0001), and social support ( r = 0.52–0.75, p < 0.0001), respectively. Conclusions: The CORe-MBC appears to be a valid and reliable tool. Further studies are planned to test the tool among diverse populations in a large academic health center and community oncology center in Chicago, IL and Memphis, TN.