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

INTRODUCTION: Existing research has linked increased patient participation in oncology care to greater patient satisfaction, enhanced quality of life, and improved healthcare utilization among patients with cancer. Yet, current measures of patient engagement and similar constructs do not reflect the unique experiences of patients with metastatic breast cancer; they also have limitations in terms of modality, cost, and potential for integration into clinical care. To address this, we sought to develop a new measure of participatory care in metastatic breast cancer care, referred to as the Capacity, Opportunity, and Resources in Metastatic Breast Cancer (CORe-MBC) that could be easily used in clinical care. METHODS: A comprehensive pool of candidate items for CORe-MBC was created with input from MBC patients, oncologists, and experts in measure development. Items were tested among 130 English-speaking patients with MBC recruited from a large academic oncology center; participants also completed validated measures of health activation, self-efficacy, satisfaction with care, and social support (e.g., emotional, informational, and tangible). Psychometric testing included exploratory factor analyses, using oblique rotations to evaluate factor structure, and parallel analysis to test for dimensionality. RESULTS: Patients' ages ranged from 34 to 90 years. The majority (82%) identified as White, one-third (34%) had less than a college degree, and almost all (99%) were female. 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 comparable measures of patient activation (r = 0.56, p <.0001) and self-efficacy (r = 0.31-0.40, p < 0.0005), and multiple measures of satisfaction with healthcare (r = 0.42-0.55, p <.0001), and social support (r = 0.52-0.75, p <.0001), respectively. CONCLUSION: The CORe-MBC measure appears to be psychometrically valid and reliable. Additional studies are ongoing to further validate use of the tool among diverse populations and within a variety of oncology practices, with the goal of providing clinicians with actionable insights to tailor and improve care.