THU0370 PERFORMANCE OF THE ANKYLOSING SPONDYLITIS DISEASE ACTIVITY SCORE (ASDAS) IN PATIENTS WITH PERIPHERAL AND AXIAL SPONDYLOARTHRITIS IN CLINICAL PRACTICE

Abstract

Background The Ankylosing Spondylitis Disease Activity Score (ASDAS) is a widely used composite measure of disease activity in axial spondyloarthritis (axSpA). Such a tool is lacking for peripheral SpA (pSpA). However, the ASDAS also assesses peripheral joint symptoms. Previously, trial data have shown that the ASDAS has high sensitivity to change and high discriminatory ability between disease states in pSpA (1). We hypothesized that the ASDAS can be used to measure disease activity in all patients with pSpA in clinical practice. Objectives To investigate the construct validity of the ASDAS in pSpA in comparison with axSpA in clinical practice. Methods Data from a registry for SpA in the Netherlands (SpA-Net) were used. Construct validity of the ASDAS was assessed by testing hypotheses about Spearman correlations with other outcomes measures including individual components of disease activity, physical functioning and health-related quality of life (HRQoL). Construct validity was also assessed by stratifying patients according to ASDAS cut-offs to compare means of different health outcomes across ASDAS states by one-way ANOVA analyses. All analyses were repeated after stratification for the presence/absence of psoriasis in pSpA. Results were compared to the performance of the ASDAS in axSpA. Results In total, 194 patients with pSpA and 222 patients with axSpA were included. Poor to high correlation was found between ASDAS and measures of disease activity (rs0.20 to 0.78), a moderate correlation was found between ASDAS and measures of physical functioning (rs0.61 to 0.64) and a poor to moderate correlation was found between ASDAS and measures of HRQoL in pSpA (rs-0.27 to -0.66) (table 1). With increasing ASDAS states, significantly worse scores were found on (other) measures of disease activity, physical functioning and HRQoL in pSpA (table 2). Stratification for the presence/absence of psoriasis showed similar results (data not shown). All results for pSpA were comparable to axSpA (see for example Table 1). Conclusion The ASDAS demonstrated similar construct validity in all patients with pSpA and axSpA in clinical practice. Therefore, the ASDAS can also be used to measure disease activity in pSpA in daily practice. Reference [1] Turina MC, et al. A psychometric analysis of outcome measures in peripheral spondyloarthritis. ARD 2016;75:1302-7. Disclosure of Interests None declared