Advancing composite outcome measures: Insights on weighting components from OMERACT 2023

Objective: The OMERACT Composite Working Group hosted a workshop at OMERACT 2023 to explore the complexities of weighting components in the development of composite outcomes. This study presents the methodology and findings of this workshop, exploring the complexities of weighting the individual components of composite outcome measures. Methods: The workshop featured a multifaceted program, beginning with a plenary session that introduced the concept of composite outcomes, shared a patient's journey with rheumatic disease through a narrative, illustrated a composite outcome for Osteoarthritis Flares, and outlined the five domains selected for this composite outcome. A breakout exercise engaged participants in ranking and assigning weights to these domains, followed by group discussions to reach a consensus on weights. The workshop concluded with another plenary session that discussed various weighting approaches, including discrete choice and conjoint analysis from the ANCAAssociated Vasculitis working group, and outlined future directions for research on composite outcome methods. Results: The breakout exercise revealed the challenges in assigning relative importance to different domains, highlighting the variability in participant perspectives. Consensus discussions highlighted the diversity in approaches to weighting, the need for appropriate methods to determine domain weights and the impact of such weights on the interpretation of composite scores. Conclusion: The OMERACT 2023 workshop underscored the significance of a systematic approach to weighting components in composite outcome development. It highlighted the complexity of achieving consensus on the importance of domains and the role of incorporating the perspectives of patient research partners in this process. Future research directions include refining weighting methodologies, moving composites through the OMERACT Filter and enhancing understanding of their implications for clinical trials. The findings contribute to the ongoing discourse on optimizing composite outcome measures in rheumatology and beyond, advocating for a balanced integration of scientific rigour and patient-centeredness in their development.