Table 1 Eight-step procedure for translation and cross-cultural adaptation of objectively-assessed outcome measures (TCCA-OAO procedure)

To produce two independent forward translations and make necessary region-specific adaptations of the test manual including task and material descriptions, and scoring instructions into the target language.

The two informed¹ translators are native speakers of the target language and profession². Translators are aware of the study objectives.

To merge the two forward translations from step 1 to form only one translation. To check comprehensiveness by a therapist/person of the target profession for consistency and adequate vocabulary.

The synthesis is done by another independent and informed person of the target profession or the project manager.

To review layout, grammar, and typography. This can be very time-consuming but it is important to provide an error-free, professional document for all following steps.

This check is done by the project manager or another person not involved in the translation process but with expertise in the target profession.

To backward translate the merged version by an informed person to assure detection of inconsistencies or conceptual errors, and discrepancies [3, 7].

The back translator should be bilingual or a native speaker of the source language and should have not seen the original before.

To review all translations, including all photo or video material showing the necessary test-specific material (e.g. wooden cubes, cups, clothes or zippers). The review should verify a consistent translation and adaptation process [3]. If the translation process fails, a second forward and backward translation is recommended [16].

This review of all translations and created documents should be done by the original authors including the material that will by used.

To adapt and re-check the merged forward translation based on the review comments and for grammatical, typographical or other errors, in particular, for consistency in the task and scoring descriptions, and client instructions (quality control step).

The project manager or one of the forward translators could do this check.

To pre-test the translated version with 2 to 4 patients including the comprehensiveness of the test manual, and the task and scoring descriptions. Emerging discrepancies of scoring or interpretation of results shall be discussed. Based on severity of required adaptations go back to steps 5 or 6.

Two professionals should test the pre-final version with patients.

To evaluate the quality factors of the trans-adapted OAO in patient studies. Depending on the OAO types of validity, reliability and responsiveness have to be determined.

This is the most time and human resources consuming part involving: patients, health professional of different disciplines, a project manager, assistants, and a statistician.