The pilot questionnaires were forward and backward translated into the languages of the participating centres of the DISABKIDS project. To harmonise translations across countries guidelines were established and each centre followed the standard internationally agreed upon procedure for questionnaire translation. First, two independent translators translated the English pilot draft version into each of the target languages. The two forward translators reviewed the translations for conceptual equivalence and decided upon a reconciled forward translation. A native speaker of the target language or professional translator performed the backward translation into English. Finally, the backward translation was compared with the pilot draft, thus reviewing the respective reconciled forward translation and thereby generating the respective final forward translation. The different languages versions were then harmonised by comparing items across languages.