An evaluation of the response category translations of the EORTC QLQ-C30 questionnaire

The aim of this study was to evaluate the translated response categories used in eight translations of the European Organisation for Research and Treatment of Cancer QLQ-C30 questionnaire, which is used in many international clinical trials. Twenty-eight of the 30 items in the questionnaire have the same four response categories: "Not at all", "A little", "Quite a bit" and "Very Much".

People with knowledge of both English and one of eight European languages were asked to complete an Internet survey. The strength (intensity) of the translated categories was assessed using two separate approaches: one using a verbal response scale and the other a visual analogue scale (VAS).

Two hundred and seventy-nine people participated in the survey. Most translations were rated similarly to English. The largest differences were for the German translation of "Quite a bit", which was rated 16.3 points lower than the corresponding English category on a 0-100 VAS.

Most of the translated categories were found to be similar to the English versions and should continue to be used. We recommend that three translated categories should be considered for revision. Similar surveys could be used to assess the categories used in other translated quality of life instruments.