To translate the functional index for hand osteoarthritis (FIHOA) into Italian and to evaluate its reliability and validity in Italian patients with hand osteoarthritis (HOA).
The original French FIHOA was translated into Italian according to the guidelines for cross-cultural adaptation and then administered to 72 outpatients with HOA, together with the visual analogue scale of pain (VAS), the Health Assessment Questionnaire (HAQ) and the Short Form Health Survey (SF-36). Test-retest reliability was verified by having all patients fill out the Italian version of FIHOA again 1 week later. Item-item analysis was performed. The Wilcoxon signed-rank test and Spearman's rank correlation coefficient were calculated to compare test and retest responses and to evaluate the degree of correlation. Internal consistency reliability was evaluated by Cronbach's alpha coefficient, and internal structure validity was appraised through factor analysis, also taking a varimax rotation into consideration. Construct validity was assessed by correlating FIHOA with other measures of functional impairment and pain using Spearman's rank correlation coefficient.
Internal consistency was high (Cronbach's α = 0.87). Test-retest reliability showed a Spearman's rho of 0.942 (p < 0.001). A significant correlation (p < 0.001) between FIHOA, VAS and HAQ and a significant negative correlation between FIHOA and SF-36 subscales were observed. FIHOA was confirmed to be a non-unidimensional scale, but in addition to the total score of the index, three subtotals of item scores were considered to provide better evaluations of finger functionality (items 3, 6, 8 and 10), wrist functionality (items 2 and 7) and hand strength (items 4 and 5) in single individuals.
The Italian version of FIHOA is a reliable and valid instrument for evaluating functional disability in Italian-speaking HOA patients.