Cross-cultural adaptation and validation of the Korean Version of the Functional Index for Hand Osteoarthritis (FIHOA)

Aim This study aimed to translate the Functional Index for Hand Osteoarthritis (FIHOA) into Korean, and establish its reliability and validity in Korean patients with hand osteoarthritis (OA). Method The FIHOA was translated into Korean (K-FIHOA) following cross-cultural adaptation guidelines. The K-FIHOA was pretested on 40 patients with hand OA. The adapted K-FIHOA was then administered to 100 consecutive hand OA patients together with the modified Health Assessment Questionnaire (mHAQ) and visual analog scale (VAS) for hand pain. The test-retest reliability of each item and total scores were assessed using Spearman's correlation coefficient and intraclass correlation coefficient (ICC). The internal consistency reliability was evaluated as Cronbach's alpha. The external construct validity was assessed using the correlation between K-FIHOA, mHAQ and hand pain VAS. Results The test-retest reliability for the total score was strong (r = 0.87 and ICC = 0.83). Cronbach's alpha was also high (0.88), which suggests that there is strong internal coherence in the test items. We identified significant correlations between K-FIHOA and mHAQ (r = 0.52, P < 0.01), mHAQ hand function score, (r = 0.57, P < 0.01) and hand pain VAS (r = 0.53, P < 0.01). Conclusion The K-FIHOA is a reliable and valid instrument for evaluating functional disability in Korean hand OA patients.