Objective: While there are several Japanese, qualitative, case studies examining psychotherapy outcome, there is a growing need for quantitative psychotherapy outcome research in Japan. This study adapted the Outcome Questionnaire-45 (OQ), one of the most common quantitative measures of clinical outcome, for use in Japan.
Method: With the help of 6 translators and 116 native Japanese pilot respondents, the original OQ was translated into Japanese following Beaton et al.'s methodology and includes forward translation, synthesis, back translation, and expert committee meetings.
Results: The study produced four pre-final versions, two pretest version, and one pilot version of the Japanese OQ. With permission from the original questionnaire developers, a few items were modified to achieve cultural equivalence. The rigorous translation and adaptation processes, evaluated through the Translation Validity Index and Content Validity Index provided semantic, content, and conceptual equivalence between the English and Japanese versions.
Conclusions: The current study partially validated the translation equivalence and cultural adaptation of the Japanese OQ. Study limitations and suggestions for further development are discussed.
Keywords: Outcome Questionnaire-45 (OQ); cultural adaptation; outcome; psychotherapy outcome; questionnaire; questionnaire translation.