The fibromyalgia impact questionnaire (FIQ) is a 10-item, patient-reported outcome measure to capture the total spectrum of symptoms and problems related to fibromyalgia. The original version of the questionnaire was developed in English and psychometrically validated. It has been translated into 8 languages and used worldwide as the only disease-specific questionnaire for measuring patient’s fibromyalgia status. In order to develop a Japanese version of the FIQ, we translated the original into Japanese and performed a linguistic validation of the translated questionnaire. The translation and evaluation were performed in a standard manner to ensure conceptual equivalence between the original and its translation: 1) forward-translation by two independent Japanese translators (English to Japanese); 2) back-translation by an English native translator (English to Japanese); and 3) a pilot testing for comprehension in patients with fibromyalgia. The original developer and two Japanese clinicians were involved throughout the validation process. As a result of the evaluation, the translation of daily activities such as “walking several blocks” and “doing yard work” proved challenging. Cultural difference was the main cause in finding equivalents. The numerical rating scales were not always completed properly; therefore, detailed scale instructions were attached to the front page of the questionnaire. Through multiple procedures, a linguistically validated Japanese version of the FIQ (JFIQ) has been successfully developed.
