Table 4b.

Content validity assessment of the new KSKSS.

	PROM development study	Content validity study	Rating of reviewers	Overall rating per PROM	Quality of evidence
Satisfaction domain of the New Knee Society Knee Scoring System	Development Study [68]	NA	+/−/?	+/−/±	High, moderate, low, very low
Relevance
1. Are the items relevant to the construct of interest?	–		+
2. Are the included items relevant for the target population of interest?	–		+
3. Are the included items relevant for the context of interest?	+		+
4. Are the response options appropriate?	–		+
5. Is the recall period appropriate?	–		?
Relevance rating	–	NA	+	±	Low
Comprehensiveness
6. Are all key concepts included?	–		–
Comprehensiveness rating	–	NA	–	–	Low
Comprehensibility
7. Are the PROM instructions understood by the population of interest as intended?	–
8. Are the PROM items and response options understood by the population of interest as intended?	–
9. Are the PROM items appropriately worded?			+
10. Do the response options match the question?			+
Comprehensibility rating	–	NA	+	±	Low
Content validity rating				–	Low

Legend: - Fail + Pass ? Insufficient information ± Inconsistent.