Background The Spondyloarthritis International Society (ASAS) published a new measurement tool to help in the assessment of disease activity in Ankylosing Spondylitis (AS) patients and as an instrument to assess treatment response in spondyloarthritis (SpA) patients. Before that, disease activity has been measuring with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) which is totally patient derived and does not include objective domains. ASAS developed a composite index – the Ankylosing Spondylitis Disease Activity Score (ASDAS) - including objective parameters for the assessment of disease activity.
Objectives To assess the discriminative ability and the correlation between BASDAI and ASDAS with disease activity in SpA patients according to the patient global score (PG) and the physician global score (PhG).
Methods We included 120 consecutive patients diagnosed of axial SpA according to the Classification Criteria of the ASAS group followed in our outpatient clinics. We recorded demographic data, disease’s specific characteristics (peripheral arthritis, dactylitis, enthesitis, uveitis and HLA-B27 positivity) and acute phase reactants (APR). Patients were classified into low and high disease activity (≥6 in a numerical rating scale from 0-10) in then PG and PhG scores. We also applied the BASDAI, ASDAS-B and ASDAS-C to all patients and correlate them with disease activity previously classified. Data was analyzed with the statistical software SPSS 15. Descriptive statistics were presented as proportions and means ± SD. Linear regresion analysis were used with either BASDAI/ASDAS with disease activity. The limit of statistical significance was located in the α error of 0,05.
Results Most patients 76 (63%) were men, the mean age was 38±14 years, 46 (38%) patients were HLA-B27 positive, likewise 32 (27%) had peripheral arthritis, 4 (3%) had dactylitis, 12 (10%) patients had enthesitis and 5 (4%) had uveitis. In our study BASDAI and ASDAS showed good correlation with disease activity measured with PG (BASDAI r=0,76, ASDAS-B 0,64 and ASDAS-C 0,68 p<0,001) and with PhG (BASDAI r=0,44, ASDAS-B 0,40 and ASDAS-C 0,42 p<0,001). Both scores showed good discriminative ability between low and high disease activity. Likewise, ASDAS B and C showed good correlation with BASDAI (0,72 and 0,68, p<0,001). APR did not show a good correlation with disease activity assessed by PG and PhG scores.
Conclusions BASDAI and ASDAS scores showed good to moderate discriminative ability and correlation with disease activity in axial SpA patients. In our study, ASDAS was not superior to BASDAI in the ability to discriminate between low and high risk in SpA patients.
M Rudwaleit, D van der Heijde, R Landewé, et al. The development of Assessment of Spondyloarthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis 2009; 68: 777-783.
C Lukas, R Landewe’, J Sieper, M Dougados, J Davis, J Braun, S van der Linden, D van der Heijde. Development of an ASAS-endorsed disease activity score (ASDAS) in patients with ankylosing spondylitis, for the Assessment of SpondyloArthritis international Society. Ann Rheum Dis 2009; 68: 18–24.
Disclosure of Interest None Declared