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

Background: To perform reliability and validity study of the Functional Index for Hand Osteoarthritis (FIHOA) in the Turkish language. Methods: FIHOA was translated into Turkish following the principles of cross-cultural adaptation. Our translation was firstly tested in 40 patients with hand osteoarthritis. Adapted FIHOA questionnaire was then administrated to 100 hand OA patients successively with Modified Health Assessment Questionnaire (mHAQ), Numerical Rating Scale (NRS), and Short Form-36 (SF-36). Patients filled out the FIHOA questionnaire one more time after five days for test-retest assessment. Patients were divided into two groups as symptomatic or asymptomatic, with a NRS score of 5 or above defining symptomatic OA. Internal consistency was assessed by Cronbach's alpha and intraclass correlation coefficient (ICC) of test-retest reliability. Spearman correlation analysis was used to determine the correlation and validity between data. External construct validity was assessed using the correlation between FIHOA, mHAQ, hand pain NRS, and negative correlation with SF-36 subgroups. Results: According to the total score, Cronbach-alpha was found as 0.90, while ICC was determined as 0.98 for test-retest reliability. When the correlations between the FIHOA questionnaire, mHAQ, and NRS questionnaires were examined, significant correlations were determined, and negative correlations between FIHOA and SF-36 subgroups were observed. Conclusion: Turkish FIHOA is a reliable and valid method for assessing functionality in Turkish patients with hand osteoarthritis.