Comparison of ASDAS and BASDAI as a measure of disease activity in axial psoriatic arthritis

The aim of this study was to compare the discriminative ability of Ankylosing Spondylitis Disease Activity Score (ASDAS) with Bath Ankylosing Spondylitis Activity Disease Activity Index (BASDAI) and other clinical disease activity parameters in patients with axial psoriatic arthritis (axPsA). Patients with axPsA were recruited from Erciyes Spondyloarthritis Cohort (ESPAC) and Anatolian Group for the Assessment in Rheumatic Disease (ANGARD) cohort and were assessed for BASDAI, ASDAS, BASFI (Bath Ankylosing Spondylitis Functional Index), Ankylosing Spondylitis Quality of Life (ASQoL), and visual analog scale (VAS) pain. The discriminant ability of ASDAS-C-reactive protein (−CRP) and ASDAS-erythrocyte sedimentation rate (−ESR) was assessed using standardized mean differences between patients with high and low disease activity. Fifty-four patients with axPsA were included in the study. Both ASDAS scores showed good discriminative ability between high and low disease activity states. Both ASDAS versions and BASDAI had relatively high area under the curve (AUC) according to ASAS partial remission, patient and physician global assessments in receiver operating characteristic (ROC) curve analysis. There was no significant difference between AUC scores for the models that compared ASDAS-CRP and ASDAS-ESR with BASDAI for each individual definition of disease activity states. ASDAS versions and BASDAI showed good similar discriminative ability between high and low disease activity as reflected by the AUC analysis in axPsA. The cutoff values for inactive disease and high disease activity were relatively similar to predefined cutoff values for AS. Further, prospective validation is now required to identify the appropriate assessment tools and cutoff values in axPsA.