Development of a child and family centred outcome measure for children and young people with life-limiting and life-threatening conditions: progress to date on the Children's Palliative Care Outcome Scale (C-POS:UK).

Background: Development of a paediatric palliative care child and family centred outcome measure is a priority for health care professionals, researchers and advocates. It is methodologically challenging to develop a measure relevant for such a heterogenous population with complex needs. Involving children in measuring development is vital. Objective: To develop C-POS:UK (Children's Palliative Care Outcome Scale, UK), a person-centred outcome measure (PCOM) for children with life-limiting conditions and their families, and to test its psychometric properties. Design: Sequential mixed-methods approach to PCOM development, guided by Rothrock's measure development process and COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) methodology. Methods: (i) Qualitative interviews about priority symptoms and concerns, with embedded exploration of measure design for children with life-limiting conditions; (ii) systematic review of measure design for children; (iii) modified Delphi survey, and consultation with children, on priority items for new measure; (iv) expert item generation meeting to develop C-POS:UK; (v) cognitive testing to refine C-POS:UK; (vi) psychometric validation. Results: (i) 106 participants described physical, emotional/psychological, spiritual/existential, social and practical concerns. Measure design was discussed by 79 participants comprising preferred response format, recall period and measure administration for children with life-limiting conditions; (ii) systematic review highlighted need for: different versions of measure accounting for child's developmental stage and cognitive ability; parent/carer involvement as proxies for very young children; and testing to clarify recall periods and response formats at different developmental stages; (iii) Delphi survey: 82 participants (in the first round), with a move towards consensus, but with some differing priorities in stakeholder groups: professionals prioritised physical symptoms, parents prioritised psychosocial and practical matters, while consulted children prioritised normality; (iv) 22 experts contributed to item generation meeting, resulting in five versions of C-POS:UK accounting for child's developmental stage and cognitive ability, and proxy involvement; (v) 48 participants cognitively tested initial C-POS:UK, informing comprehension, comprehensiveness and acceptability; (vi) psychometric validation is ongoing. Conclusion: A sequential approach informed by Rothrock and COSMIN has supported development of the first version of C-POS:UK. Psychometric validation is underway and will be followed by implementation planning.