The development and initial validation of an outcome measure for children and young people with life-limiting and life-threatening conditions

A sequential mixed-methods study was conducted in three phases, following the principles of patient-reported outcome measurement design described by Rothrock and the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN).

To inform face and content validity of C-POS a semi-structured qualitative interview study was conducted to seek the perspectives of children and young people, their parents/carers and siblings, health care professionals and NHS commissioners on priority symptoms, concerns, and care priorities. Participants were also asked to identify their preferences for the design of C-POS, in terms of recall period, response scale format and administration mode.

Part 1: Parents and professionals with experience in caring for a child or young person with a life-limiting or life-threatening condition participated in a three-round modified ranking-type Delphi survey with the aim of establishing which outcomes identified in phase 1 of this thesis should be included in C-POS.

Part 2: The young person’s advisory group were asked to select their priority outcomes from the items ranked in rounds 2 and 3 of the Delphi survey.

Cross-sectional cognitive interview study to establish acceptability, comprehensiveness, and comprehension of the initial C-POS versions within the target population.

Phase 1 - gathering input

Systematic review: Findings showed that children under five years old cannot validly and reliably self-report health outcomes. Face scales demonstrated better psychometric properties than visual analogue or Likert scales. Computerised and paper scales generally show equivalent construct validity and children prefer computerised measures. Children seven years old and younger often think dichotomously so may need two response options. Those over eight years old can reliably use a three-point scale.

Qualitative interview study: 106 participants were recruited: 26 children, 40 parents, 13 siblings, 15 health care professionals and 12 commissioners. Children found a short recall period and a visually appealing measure with 10 questions or fewer most acceptable. Children with life-limiting conditions were more familiar with using rating scales such as numeric and Likert than their healthy siblings and emphasised the importance of completing the measure alongside interactions with a healthcare professional. Parents assumed that electronic completion methods would be most feasible and acceptable but a small number of children preferred paper measures.

Part 3: 22 participants attended the item generation meeting. Five

age/developmental stage appropri

Forty-eight individuals participated (36 parents; 12 children) in cognitive testing of the C-POS versions. This revealed challenges in the acceptability of some items for parents of non-verbal children and refinements were made. C-POS content and length were acceptable, and all questions were considered important. Parents reported that completing a measure that asks about what matters may be distressing but this is anticipated and acceptable.

This thesis demonstrates the development of the first UK patient-centred outcome measure for use with children and young people with life-limiting and life-threatening conditions and their families. By following established methodological criteria for patient-centred outcome measure development this thesis demonstrates that CPOS has robust face and content validity and is feasible and acceptable for use within the target population.