Simplified Ankylosing Spondylitis Disease Activity Score (SASDAS) Versus ASDAS: A Post Hoc Analysis of a Randomized Controlled Trial

Abstract

Objective To compare the Simplified Ankylosing Spondylitis Disease Activity Score (SASDAS) against the Ankylosing Spondylitis Disease Activity Score (ASDAS) for measuring and categorizing disease activity using data from the EMBARK trial (ClinicalTrials.gov: NCT01258738), a randomized controlled trial of etanercept (ETN) for axial spondyloarthritis (axSpA). Methods Patients with early active axSpA received ETN 50 mg once weekly (n = 106) or placebo (PBO; n = 109) for 12 weeks in a double-blind manner; they then received open-label ETN for 92 weeks. For this analysis, ASDAS–C-reactive protein (CRP) and SASDAS-CRP were calculated at baseline, week 12, and week 24. The SASDAS was calculated by the linear addition of the ASDAS components without adjustment. Results A very strong correlation, as determined by the Spearman correlation coefficient, was observed between the ASDAS and SASDAS for continuous variables at baseline and during treatment. For pooled categorical data at baseline, the SASDAS placed 69.9% of patients in the same disease categories as the ASDAS but overestimated for 17.8% of patients and underestimated for 12.2% of patients. A similar pattern was seen postbaseline. Cohen weighted κ statistics for all individual and pooled treatments and timepoints (0.54-0.73) reflected moderate to substantial agreement. The capacity to differentiate between treatments (ie, ETN and PBO/ETN) was higher with the ASDAS (effect size –0.74, 95% CI –1.03 to –0.46) compared with the SASDAS (effect size –0.51, 95% CI –0.79 to –0.23), but sensitivity to change was generally similar. Conclusion A very strong correlation between the SASDAS and ASDAS was observed when considering continuous variables; however, moderate to substantial agreement was observed for categorical data, and the SASDAS classified a lower proportion of patients as being in the inactive and low disease activity categories.

Further Simplified Clinimetry Using a Multidimensional Health Assessment Questionnaire

“…

We agree that it is "good to simplify clinimetry in chronic inflammatory joint diseases, " as suggested by DiCarlo and Salaffi in a recent editorial 1 concerning an article by Schneeberger et al, which showed that a Simplified Ankylosing Spondylitis Disease Activity Score (SASDAS) was similar to an ASDAS. 2 We note that the very high correlations of the SASDAS with the ASDAS 2 are largely predictable, as the 5 measures in the 2 indices are identical, albeit with weighting in the ASDAS, although confirmation is reassuring.The reported measures are from a clinical trial setting, as a formal ASDAS (or SASDAS) generally is not collected in most busy routine care settings. 3 We suggest that more feasible "simplified clinimetry" is provided by Routine Assessment of Patient Index Data 3 (RAPID3) on a Multidimensional Health Assessment Questionnaire (MDHAQ), which has been documented in several studies to be strongly correlated with the ASDAS.

…”

“…We agree that it is "good to simplify clinimetry in chronic inflammatory joint diseases, " as suggested by DiCarlo and Salaffi in a recent editorial 1 concerning an article by Schneeberger et al, which showed that a Simplified Ankylosing Spondylitis Disease Activity Score (SASDAS) was similar to an ASDAS. 2 We note that the very high correlations of the SASDAS with the ASDAS 2 are largely predictable, as the 5 measures in the 2 indices are identical, albeit with weighting in the ASDAS, although confirmation is reassuring.…”

Axial spondyloarthritis: one year in review 2023

“…The Ankylosing Spondylitis Quality of Life (ASQoL) score has been validated in nr-axSpA for the assessment of patients' QoL (44), while a post-hoc analysis of a randomised controlled trial (RCT) observed a strong correlation between the Simplified Ankylosing Spondylitis Disease Activity Score (SASDAS) and the ASDAS. The authors suggest that, while the SAS-DAS is not intended to replace the gold standard ASDAS measure of disease activity in axSpA, it may be useful as a simplified tool in some situations (45). Two recent meta-analysis showed that biological therapies, in particular TNF-inhibitors (TNFi) and anti-IL-17 agents, seem to be related to an improvement in Short-Form 36 (SF-36) and ASQoL scores of patients with AS, when compared to non biological treatments or placebo (46,47).…”