The purpose of this study was to translate the Rheumatoid Arthritis Disease Activity Index-5 (RADAI-5), which is a tool for measuring disease activity in rheumatoid arthritis (RA) patients, into Turkish language and prove its validity, reliability and sensitivity to changes.
Translation from the original German version was performed according to the standardized methods. One hundred and two patients with RA completed in the Turkish RADAI-5 twice within 3 days interval. Internal consistency and test-retest reliability was investigated by calculating Cronbach's alpha and intra-class correlation coefficients (ICC), respectively. Validity was assessed by analyzing the correlations between the Turkish RADAI-5 and some measurement tools evaluating the disease activity, functional status and quality of life. To test the scale's responsiveness to the changes, another 23 patients with uncontrolled disease activity and three newly diagnosed RA patients completed the RADAI-5 before and after a biologic agent or methotrexate treatment.
There were no floor or ceiling effects. Cronbach's alpha (0.91) and ICC (0.997) values certified the Turkish version's reliability. Strong correlations between the Turkish questionnaire and Disease Activity Score-28 (DAS28), DAS28-CRP, DAS28-three variables, Health Assessment Questionnaire, Rheumatoid Arthritis Quality of Life questionnaire, patient's and doctor's global assessments, tender joint count proved the convergent validity of the scale. Effect size (3.08) demonstrated that the Turkish RADAI-5 is sensitive to the changes.
The Turkish RADAI-5 is a feasible, reliable and valid questionnaire and sensitive to changes; thus it can be used to monitor disease activity in Turkish RA patients.