Instrument translation of CVID QoL
To ensure a linguistic equivalence with the original questionnaire, the
cross- cultural validation process was conducted according to an
international consensual systematic methodology, called standardized
linguistic validation21, 22. Permission to translate
and validate CVID QoL into Turkish language was obtained from the
original questionnaire developer (Dr Pulvirenti and Dr Quinti, author on
this manuscript). Two separate forward translations from Italian to
Turkish involving two independent both bilingual but native speakers
were conducted, and they were reconciled into one version. Then the
backward translation of the reconciled version into Italian was made by
native speakers. The backward translation was compared with the original
Italian questionnaire by the expert committee. Afterwards the pre final
Turkish version of questionnaire was obtained. (Figure 1.) In this
version, the content validity index was determined for each item by ten
experts by using the options of 1= “not suitable”, 2= “partially
suitable, applicable by modification”, 3= “the item available as it
is”. After this step, the Turkish version of the questionnaire was
applied individually to five eligible patients as a pilot study.
Meanwhile, we got their comments on whether all 32 items were
understandable and suggestions for changes. Finally, the last version
CVID QoL was approved.