Exploring the validation of a Japanese version of the International Hip Outcome Tool 12: Reliability, validity, and responsiveness.

Backgrounds: The International Hip Outcome Tool 12 (iHOT12) was authorized by the Multicenter Arthroscopy of the Hip Outcomes Research Network (MAHORN). iHOT12 is increasingly being adopted in orthopedic studies to report patient outcomes. This study aimed to develop a Japanese version of the International Hip Outcome Tools "iHOT12J", and to establish its reliability, validity, and responsiveness.

Methods: To assess test-retest reliability, an identical set of patients reported outcome measures with five qualitative scoring measures including iHOT12; these were filled out by each patient twice. Reliability was explored using Cronbachss alpha and intraclass correlation coefficient. The Bland-Altman plot was used to explore the absolute agreement. To evaluate validity, we examined the relationships between SF36 and iHOT12. Responsiveness was assessed by comparing the smallest detectable change to the minimal important change by applying an anchor-based approach.

Results: Fifty patients (51 joints) were analyzed from March 2016 to October 2017 in Japanese four facility. The Cronbach α coefficient was 0.90 and the average value of intraclass coefficient (ICC) was 0.89. Bland-Altman plot analysis showed a solid agreement. Regarding the validity, the Spearman rank correlation coefficients were strong with PF (r = 0.69, p < 0.01), BP (r = 0.71, p < 0.01) and PCS (r = 0.69, p < 0.01). The smallest detectable change (3.19) was smaller than the minimum important change (12.40).

Conclusions: We developed iHOT12J, which seems to show sufficient reliability, validity, and responsiveness. We believe that this patient reported outcome measure is beneficial in studying Japanese patients with femoroacetabular impingement.