Table 3.

Main findings from cognitive interviews with children and young people.

Item number	C-POS item	Comprehension	Retrieval	Judgement	Response	Changes made to response format	Changes made to question
1	Hurt (5–12 years) Pain (13–17 years)	Good comprehension in those over 8-years-old a . Younger children a understood after a verbal explanation. Question answered in terms of frequency, rather than severity or impact pain had on day-to-day life.	The majority of those 8- to 17-year a could recall the past week. Some interpreted this to mean since Monday or the start of the weekend. Some 5- to 7-year a struggled with yesterday and could only report on the current day.	Those 5- to 7-year a needed some help from a parent to integrate their thoughts into a response. Those 8- to 17-year a had no difficulties.	Some concerns that those 5- to 7-year a chose the response they thought the interviewer wanted to hear. Emojis made choosing easier. 8–12 years a showed variability in ability to use a 5-point response format. Those 13- to 17-year a all preferred and could use 5-point response format.	‘Most of the time’ replaced with ‘All of the time.	Quantifiers removed from beginning of question (How much, how often etc) to allow severity and impact to be reported in addition to frequency.
2	Other problems with your body	Well-understood by those 8- to 12-years old a . Young children sometimes needed a verbal explanation. One participant included emotional problems. Question answered in terms of frequency, rather than severity or impact symptoms had on day-to-day life.	The majority of those 8- to 12-year a could recall the past week. One 5- to 7-year-old a could only remember the current day.	No problems integrating thoughts into a response.	Those 5- to 7-year a could use the 3-point response format. About 8–12 years a showed variability in ability to use a 5-point response format. Those 13- to 17-year a all preferred and could use 5-point response format.	As above	Quantifiers as above
3	Worry	Good comprehension in all participants except one 5- to 7-year-old a .	All those 8- to 12-year a could recall the past week. One participant 5- to 7-year a could not understand the recall period yesterday and today and discussed salient events in the recent past.	All but one participant (5–7 years a ) could integrate their thoughts into an appropriate response.	As above	As above	Quantifiers as above
4	Sharing feelings	Good comprehension. One 5- to 7-year-old a required a verbal explanation from parent to understand the question.	All participants could retrieve the information required. All those 8- to 12-year a except one participant could recall the past week.	No problems integrating thoughts into an appropriate response.	As above	As above	Quantifiers as above ‘Sharing feelings’ changed to ‘been able to talk to people’ in 5- to 7-year-old a version
5	Being able to do the things you usually would	Good comprehension.	One child 5- to 7-year a could only recall the current day. One child 8- to 12-year a thought back to the start of the weekend (interview was a Wednesday).	Several children 5- to 7-year-old a wanted clarity regarding whether usual things were those done currently, pre-diagnosis or pre COVID-19 pandemic.	As above	As above	Quantifiers as above
6	Being able to do things that are fun (5–7 years) Being able to do things you enjoy (8–17 years)	Good comprehension – all could explain the difference between ‘usual activities’ and ‘fun things/things you enjoy’.	Those 5- to 7-year a could recall yesterday and today. Those 8- to 17-year a could recall the past week, although one referred back to start of the week (interview was mid-week).	No major problems integrating thoughts into a response. One participant asked same question as above regarding pre/post diagnosis and COVID-19 pandemic.	As above	As above	Quantifiers as above
7	Enjoying life as much as possible (5–7 years) Living life to the fullest (8–17 years)	Younger children understood ‘enjoying life as much as possible’. For children aged 8–12 a only half understood ‘living life to the fullest’. The rest preferred the 5- to 7-year a question. Children 13- to 17-year a could comprehend and explain what living life to the fullest meant to them.	One child 5- to 7-year a answered generally without relating response to required recall period. Those 5- to 7-year a could recall the past week. One 8- to 12-year-old a expressed a preference for a recall of yesterday and today.	No problems integrating thoughts into a response.	As above	As above	Quantifiers as above ‘Living life to the fullest’ changed to ‘Enjoy life as much as possible’ in 8- to 12-year-old a version
8	Being able to ask important questions	No problems with comprehension in those 5- to 7-year a . Younger children needed a verbal explanation of what the question meant.	One 5- to 7-year-old a could only recall the current day. Those 12- to 17-year a could recall the past week.	No problems integrating thoughts into a response.	As above	As above	Quantifiers as above

^aOr cognitive equivalent.