Japanese version of the Oral Health Impact Profile (OHIP-J)

The objective of the study was to develop a Japanese version of the Oral Health Impact Profile (OHIP). The original 49 items were translated using a forward-backward method following accepted cultural adaptation guidelines. A de novo development of Japanese items was conducted to establish content validity. The associations between the OHIP summary score and self-reported oral health (n = 220) and self-reported denture quality (n = 155) were investigated for construct validity. The association between the OHIP summary score and six oral conditions (n = 227) were also tested. The responsiveness of the instrument was established by comparing the score before and after using newly fabricated removable partial dentures (n = 30). The test-retest reliability (n = 37) and internal consistency (n = 251) were also calculated. After the de novo development, five new items were added to the OHIP. The priori hypothesized associations between the OHIP score and oral health conditions were confirmed (P < 0.001). The change in the OHIP scores from 63.6 to 40.6 (P < 0.001) supports the responsiveness of the instrument. Intra-class correlation coefficients of 0.81 and Cronbach's alpha of 0.98 indicate high test-retest reliability and internal consistency of the instrument's summary score. Sufficient discriminative and evaluative psychometric properties of the currently developed Japanese version of the OHIP in typical target populations make the instrument suitable for assessing the oral health-related quality of life in cross-sectional as well as longitudinal studies.