A novel child-centred core palliative care outcome measure for use in clinical practice and research: findings from a multinational validation study.

Abstract

Background: Outcome measurement is pivotal to person-centred assessment, quality improvement and research. Children and young people with life-limiting and -threatening illness have high needs and service use, yet there is a lack of evidence for interventions and care models. Efforts to strengthen paediatric palliative care (PPC) services has been hampered by the lack of an appropriate outcome measure.

Objective: To determine the validity, reliability, measurement invariance, responsiveness, acceptability, and interpretability properties of the novel Children's Palliative care Outcome Scale (C-POS).

Methods: We recruited children (0-17 years) with life-limiting/life threatening conditions and their families in Kenya, Uganda and South Africa. Using C-POS repeated measurement using over four timepoints. We assessed: 1) construct validity (structural properties, discriminant validity, known groups validity, measurement invariance, differential item functioning by country), 2) reliability (internal consistency and test re-test), 3) responsiveness, 4) acceptability (time to complete) and 5) interpretability.

Results: We recruited a cohort of 434 children (response rate 94%). Of these, 302 participated in the repeated measures component and 279 (92%) completed four datapoints. We found evidence for face and content validity as the C-POS items mapped on to themes developed from qualitative interviews, including: pain and other symptoms, pyscho-social well-being, and family wellbeing that matter to children and their families. We confirmed: 1) the two-factor structure (child and family subscales). We also confirmed discriminant and known groups validity, as well as construct equivalence for the child self-report and proxy versions. Controlling for age, we found no differential item functioning by country setting. 2)The sub-scale internal consistency was moderate, given the multi-dimensional nature of the C-POS self and proxy report versions omega scores (0.67 and 0.73, respectively). The test characteristic curve information confirmed the moderate internal subscale consistency scores between 0.3- 0.9 for the proxy version and 0.3-0.5 for the self-report version. Test-retest reliability was acceptable for all items, with weighted kappa range for scores: self-report (0.43-0.57) and proxy version (0.35-0.64) and family items (0.51-0.71). 3)Responsiveness was demonstrated, except for the feeding item. 4)Median completion time at the last visit was 10 min for both versions with minimal missing data. 5)The minimum important difference was 3 for the self and proxy report versions on a scale of 0-30 and 4 for the child and family scale on a scale of 0-55.

Conclusions and relevance: The C-POS has good psychometric properties. To further improve the measure, we identified items for potential removal, conceptual gaps that should be addressed and domains for which developmental age-appropriate items are needed. C-POS has potential to evaluate and improve person-centred children's palliative care in research and routine clinical practice.