The Reliability and Validity of a Korean Translation of the BASDAI in Korean Patients with Ankylosing Spondylitis

ObjectivesThe objective of this study was to develop a Korean version of the original English version of BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) and to evaluate its reliability and validity in Korean patients with Ankylosing Spondylitis (AS).MethodsA total of 50 outpatients diagnosed as AS by the modified New York criteria participated. To develop a Korean version of the BASDAI, we followed rigorous international translation steps and evaluated reliability and validity by calculating Cronbach's alpha and correlation coefficients between BASDAI score and clinical parameters (e.g., ESR, CRP, modified Schober test index, finger-to-ground index, and Bath Ankylosing Spondylitis Radiologic Index Score, and bone mineral density).ResultsCronbach's alpha (= 0.75) was acceptable. The distribution of item responses evaluated by the ceiling and floor effects showed appropriate proportions and a good discrimination with the Korean version of the BASDAI. The correlations among the mean BASDAI score and five scales for the convergent validity was significantly correlated with each other (all P-values < 0.01). The correlations between the BASDAI score and both erythrocyte sedimentation rate and C-reactive protein for the criterion validity were positively correlated (all P-values < 0.05). The results of this study showed that the Korean translation of the BASDAI is an efficient tool in terms of its reliability and validity for the measurement of the disease activity in patients with AS.ConclusionsThe Korean version of the BASDAI could be used in clinical research to assess and evaluate the course of disease activity in Korean AS patients.