Improving Measurement and Priorities for Assessment in Clinical Trials of childhood-onset Dystonia International Core Outcome Set (Dystonia IMPACT-COS): A protocol.

INTRODUCTION: Dystonia is a movement disorder characterised by abnormal movements and/or postures, initiated or worsened by voluntary action. Non-degenerative childhood dystonia is common, represents a substantial source of lifelong disability, and is often associated with other motor and non-motor phenotypes that can contribute to functional impairments. However, there is no consensus on how to measure motor and non-motor outcomes associated with dystonia, nor is there consensus on what outcomes to measure. This prevents adequate evaluation and development of evidence-based interventions and decision-making in clinical practice. Here, we present the protocol for establishing global expert consensus on the Dystonia Impact Core Outcome Set (DI-COS) to describe what dystonia-associated outcomes to measure and how to measure them. METHODS AND ANALYSIS: The DI-COS study includes a mixed-methods programme with three phases. Phase 1 includes; (i) scoping review, (ii) qualitative interview study with children and families, and (iii) international survey of health, social care, and education-based professionals. Phase 2 is a three round international e-Delphi study informed by Phase 1, and expert consensus from: (i) a professional panel and (ii) experts with lived experience (parents and children). Content and thematic analysis, and descriptive statistics will be used to analyse qualitative and quantitative data, respectively. Results will be triangulated to inform development of the Delphi survey in Phase 2. Phase 3 will identify the outcome measures available and recommend assessment outcomes agreed as part of Phase 2 Consensus. ETHICS AND DISSEMINATION: Ethical approval has been obtained from Camden and King's Cross Research Ethics Committee (25/LO/0150) and Queen Mary, University of London Research Ethics Committee. All dissemination activities (including papers submitted to peer-reviewed journals, abstracts submitted to national/international conferences, visual outputs and engagement events), will be co-produced, co-designed and co-presented/authored with members of the study's advisory groups and shared via project's networks.