Background/Purpose: There is a high prevalence of upper limbs involvement in Rheumatoid Arthritis (RA), with a lack of useful tools in daily practice assessing the functional capacity of this particular anatomical region. Dreiser et al. developed the Functional Index for Osteoarthritis of hands (FIHOA), aimed to evaluate the functional capacity of patients with hand osteoarthritis (HOA), whose Argentinian version was validated 2016. However, this instrument has not been validated yet in patients with RA. The aim of this study was to validate FIHOA in RA patients.

Methods: Analytical, observational, prospective cross-sectional study including consecutive patients with diagnosis of RA (ACR/EULAR 2010). Demographic and RA characteristics, disease activity measures and treatment were recorded. Patients completed the following self-administered questionnaires: HAQ-A (Health Assessment Questionnaire Argentine Version), HAQUP (Health Assessment Questionnaire-Upper extremity), FIHOA and Quick DASH (Quick Disabilities of the Arm, Shoulder and Hand). For a patient subgroup, an occupational therapist performed an objective evaluation of the functional capacity of the upper limbs using the Sequential Occupational Dexterity Assessment (SODA). To assess reproducibility, 30 patients with similar clinical and therapeutic conditions to their first evaluation completed the questionnaire again 10 to 15 days later. Statistical analysis: Patient and disease characteristics were described with means, medians, absolute numbers, proportions, standard deviation (SD) and interquartile ranges (IQR). Reliability was assessed using the Cronbach test. Construct validity was analyzed through the correlation with other functional capacity questionnaires and disease activity parameters using the Spearman coefficient. Reproducibility was estimated using test-retest reliability. A linear regression model was constructed with FIHOA as the outcome variable and those variables that proved significant on bivariate analysis.

Results: We included 100 patients, 83% women, mean age 57.9 years (SD 11.6). Cronbach’s alpha test was 0.94. There were no redundant questions by inter-item correlation. FIHOA showed an excellent correlation with HAQ-A (r = 0.89); HAQUP (r = 0.89); Quick DASH (r = 0.90) and SODA (r =-0.80). It also showed good correlation with DAS28 (r = 0.65) and other composite disease activity measures as well as with other disease parameters [visual analog scale (VAS) for pain, patient and physician global assessment of the disease, tender and swollen joint count]. There was no correlation between FIHOA and age or disease duration. Questionnaire reproducibility was 0.73. A multiple linear regression adjusted for age and sex showed morning stiffness as the main determinant of FIHOA, followed by patient global assessment VAS and glucocorticoid use.

Conclusion: FIHOA was found to be reliable, valid and reproducible in patients with RA, providing a valuable tool for the evaluation of functional capacity of the upper limbs in these patients.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/validation-of-the-functional-index-for-hand-osteoarthritis-fihoa-in-patients-with-rheumatoid-arthritis/