Table 1 Methodological criteria for the translation process and cross-cultural validation [9]

1

Was the percentage of missing items given?

2

Was there a description of how missing items were handled?

3

Was the sample size included in the analysis adequate?

4

Were both the original language in which the HR-PRO instrument was developed,

and the language in which the HR-PRO instrument was translated described?

5

Was the expertise of the people involved in the translation process adequately described?

e.g. expertise in the disease(s) involved, in the construct to be measured, or in both languages

6

Did the translators work independently from each other?

7

Were items translated forward and backward?

8

Was there an adequate description of how differences between the original and

translated versions were resolved?

9

Was the translation reviewed by a committee (e.g. original developers)?

10

Was the HR-PRO instrument pre-tested (e.g. cognitive interviews) to check interpretation,

cultural relevance of the translation, and ease of comprehension?

11

Was the sample used in the pre-test adequately described?

12

Were the samples similar for all characteristics except language and/or cultural background?

13

Were there any important flaws in the design or methods of the study?

14

for CTT: Was confirmatory factor analysis performed?

15

for IRT: Was differential item function (DIF) between language groups assessed?