AB0554 Basdai or asdas in axial spondyloarthritis: which score choose to evaluate response to tnf alpha-blockers, according to c-reactive protein?

Objectives to compare proprtions of responders to infliximab according to the level of C-reactive protein (CRP) in a population of axial spondyloarthritis (AS) defined with the ASAS 2009 criteria set. Methods 106 AS patients, fulfilled the ASAS criteria, were included in this monocentric, observational and retrolective study, conducted between 2001 and 2011, in the rheumatologic department of Rouen University Hospital (France). All patients were treated by infliximab (5 mg/kg at week 0, 2, 6 and every 8 weeks). Their response to infliximab was evaluated at 6 and 12 month with ASDAS and BASDAI calculated retrospectively. The percentages of responders with BASDAI (improvement of 50% or at least 2 points) and ASDAS responders (improvement ≥ 1,1 point) were compared at 6 and 12 month for overall patient and according the CRP level (> 5 mg/l or < 5 mg/l) before treatment. Results Among the 106 AS patients (57 women and 49 men), 56 had raised CRP while 50 had normal CRP. Under infliximab, BASDAI decreased from 6 (4-9.4) to 3.6 (0-5.9) at 6-month and to 3.6 (0-5.9) at 1 year. ASDAS decreased from 3.6 (2.1-5.7) to 2.5 (0.83-4.25) at 6-months and to 2.3 (0.7 – 4.4) at 12 months. At 6-month, the percentages of BASDAI and ASDAS responders were respectively 52,8% and 43,4% for overall patient (p=0,012), 60,7% and 57,1% (p=0,41) when CRP is elevated, and, 44% and 28% in the normal CRP group (p=0,0114). At 12-month percentage of BASDAI and ASDAS responders was respectively 49,1% and 46,2% for overall patients (p=0,56); 55,4% and 60,7% in the raised CRP group (p=0,18) and 42% and 30% in the normal CRP group (p=0,014). Moreover, BASDAI and ASDAS scores were better correlated in absence of inflammatory syndrome. Conclusions This study have shown for the first time that when CRP is high, ASDAS and BASDAI classify similarly the AS patients while when CRP is normal, BASDAI classify more responders than ASDAS. So, ASDAS criteria could be used when baseline CRP is high but BASDAI criteria seem more appropriate than ASDAS when CRP is normal in this cohort of AS patients treated with infliximab Disclosure of Interest None Declared