P179 Perpetual dilemma: international multicentre study correlating BASDAI and ASDAS (CRP) as a marker of disease activity in spondyloarthritis
Authors: Jain Nibha , Pandya Sapan , Srivastava Puja , Shukla Dhaiwat , Moorthy Arumugam 
Published: April 2021

Abstract
Background/Aims
While BASDAI is one of the most widely used tool it has limited face and construct validity. ASDAS on the other hand is considered more objective ,however in absence of blood investigations, it might not be an ideal measure. We aimed to study correlation and agreement between ASDAS-CRP with BASDAI score. We correlated these outcome measures with MRI activity
Methods
This was a multi-centre study, conducted at rheumatology department of two teaching hospitals in United Kingdom and India. Anonymised data of all consecutive patients with the clinical diagnosis of SpA were analysed. We compared outcome measure variables ASDAS-CRP with BASDAI at baseline and follow-up with subgroup analysis of BASDAI cutoff of 4. We also analysed radiological parameters and compared disease activity of patients with active changes of SpA in MRI versus those with inactive changes . SPSS software and Cohen’s kappa statistics used
Results
Total 250 patients with SpA were analysed with median age of 34 years and total duration of 5.9 +6 years. Mean BASDAI 4.9 +8.8, Mean ASDAS-CRP 3.04 + 3.5, Mean CRP 19.32 +12.8 mg/l. The Correlation between BASDAI and ASDAS-CRP (r) was 0.76 and the correlation coefficient of agreement between ASDAS-CRP and BASDAI &gt;4 was 0.75.The cutoff point of ASDAS with the best agreement with BASDAI was 3.5 (global agreement 78%, kappa 0.55). Both BASDAI and ASDAS showed a higher correlation with patient’s global assessment (PtGA) (r = 0.82 and 0.74, respectively) than with physician’s global assessment(PhyGA) (r = 0.76 and 0.7) The discriminant validity analysis showed that both ASDAS and BASDAI were able to discriminate patients above and below median PtGA (d = 1.15 &d=1.3) and PhyGA (d = 0.75 and d = 0.9) respectively however BASDAI was better than ASDAS to discriminate patients above and below the median PhyGA (p = 0.05)60 patients were followed up with mean duration of follow-up of 6.2 +1.6 months. Both ASDAS and BASDAI decrease significantly (p = 0.03 and 0.02 respectively) however effect size was greater for ASDAS(0.8) than BASDAI (0.6). There was no difference noted in the degree of spinal inflammation as evidenced by MRI when patients with BASDAI &gt;4 were compared to &lt; 4. (p = 0.43, OR 0.6). The correlation between ASDAS and BASDAI was much higher in patients with active MRI lesions (r = 0.84), without any difference in CRP or BASDAI (p = 0.8 and p = 0.66 respectively)
Conclusion
This is a first study involving India and UK, which systematically compares the disease activity and outcome measures. Although BASDAI and ASDAS correlate well, the agreement is better for patients with high disease activity. ASDAS is more sensitive to change and shows larger effect size on follow-up. The outcome measures correlated more with active MRI lesions. Thus the cutoff value of BASDAI &gt;4 for active disease might need a revision in clinical practice
Disclosure
N. Jain: None. S. Pandya: None. P. Srivastava: None. D. Shukla: None. A. Moorthy: Honoraria; Speaker and Conference fee MSD, Novartis Abbvie.