THU0444 CROSS-CULTURAL TRANSLATION, ADAPTATION AND VALIDATION OF A JAPANESE VERSION OF THE FUNCTIONAL INDEX FOR HAND OSTEOARTHRITIS (J-FIHOA)

Abstract

Background Hand osteoarthritis (HOA) is a highly prevalent and heterogeneous musculoskeletal disorder. Although well-designed clinical trials and guidelines have been published, there are comparatively few HOA studies concerning Asian countries. To both pursue appropriate clinical courses for patients and to engage in future research, physicians need to discriminate symptomatic HOA. The Functional Index for Hand OsteoArthritis (FIHOA) assesses hand OA-related functional impairment and is accepted as a gold standard with excellent reliability and responsiveness[1,2]. Objectives Our objective was to make a Japanese version of the FIHOA (J-FIHOA) and to validate it among Japanese HOA patients. Methods J-FIHOA was created following forward/backward translation processes distilled from the established guidelines. A prospective, multicenter study was undertaken for its validation. Seventeen collaborating hospitals recruited hand OA patients from September 2017 to September 2018. Patients who met the ACR classification criteria were included. A medical record review and the following patient-rated questionnaires were collected: J-FIHOA, Japanese Health Assessment Questionnaire (J-HAQ), numerical rating scale for pain (NRS pain) and Japanese Short Form 36 Health Survey (J-SF-36). As item 7 is a gender-role question, an item total correlation needed to be calculated independently for women and men.The J-FIHOA scores at enrollment were used to assess Cronbach’s alpha coefficient/item-total correlation and compared with the J-HAQ, NRS pain and J-SF-36 yielding respective Spearman’s rank correlation coefficients. To assess reliability, we used test-retest methods for patients with unchanged symptoms/treatments. The interval was 1-2 weeks and data sets were assessed with the intraclass correlation coefficient (ICC). To evaluate responsiveness, those who started new pharmacological treatments were required to answer the questionnaires and to have a 1-month follow-up visit. Differences between pre- and post- pharmacological treatments were used to calculate the effect size (ES). Results Twenty-nine male and 145 female HOA patients participated (mean age 65 years). Cronbach’s alpha was 0.91, showing high internal consistency. Each item was well correlated with the total score (all values >0.30; range 0.46 to 0.89). Construct validity between J-FIHOA and other scales was: 0.73 (J-HAQ), 0.56 (NRS pain), -0.31 (J-SF-36 physical component) and -0.21 (J-SF-36 mental component). Although the FIHOA has no pain-related question, previous reports showed moderate correlations between the FIHOA and pain. Our results were concordant with these reports. It was expected that J-SF-36 mental component had the weakest correlation. One hundred fifty-seven longitudinal data sets were pooled and used to evaluate reliability (137 for test-retest) and responsiveness (20 for ES). ICC for test-retest was 0.83 (95% CI, 0.77 to 0.88). The ES were 0.56 for J-FIHOA and 0.44 for J-HAQ. We assumed that this higher ES related on the HOA specificity of J-FIHOA. Conclusion We created a cross-culturally adapted J-FIHOA. Our results showed its good metric qualities to assess dysfunction in HOA and equivalence with the original FIHOA.