Table 1 List of abbreviations
| COMET | Core Outcome Measures in Effectiveness Trials |
| COS | Core outcome set(s) |
| CYP | Children and young people |
| iCAN | International Children’s Advisory Network |
| NHS | National Health Service |
| NIHR | National Institute for Health Research |
| PoPPIE | People and Patient Participation, Involvement and Engagement |
| PPI | Patient and public involvement |
| YPAG | youth patient advisory group |