ASDAS HIGH DISEASE ACTIVITY MAY BE A BETTER SELECTION CRITERION THAN BASDAI ELEVATION FOR THE TREATMENT OF ANKYLOSING SPONDYLITIS PATIENTS WITH ANTI-TNF THERAPY

Background: Elevated BASDAI (>4cm on 10cm visual analogue scale) is recommended for the selection of anti-TNF candidates in clinical practice (1). The cut-offs for elevated disease activity of the ASDAS have recently been published (2). Objectives: To investigate which cut-off for elevated disease activity is best used for selection of candidates for anti-TNF therapy in studies and clinical practice. Methods: Cross-sectional data of AS patients (NY modified criteria) included in the Regisponser registry were used. The proportion of patients with elevated disease activity using different definitions was calculated: BASDAI≥4cm (elevated BASDAI), ASDAS≥1.3 (moderate/high ASDAS) and ASDAS≥2.1 (high ASDAS). Their profile for the following variables that have been associated with good outcomes to anti-TNF therapy (3-5) was compared: low age, low BASFI, elevated CRP, HLA-B27 genotype and absence of enthesitis. The resulting population- characteristics help appreciate the appropriateness of disease activity cut-off. Results: Of 1300 Regisponser patients, 666 had elevated BASDAI. Of these, 665 and 622 had moderate/high and high ASDAS respectively. Of 634 patients without BASDAI elevation, 477 (75%) and 228 (36%) had ASDAS≥1.3 and ≥2.1 respectively. Patients without BASDAI elevation but moderate and/or high ASDAS were younger, more frequently HLA-B27 positive, had higher CRP values and less enthesitis than patients without BASDAI and ASDAS elevation. Among patients with elevated BASDAI, CRP was higher and BASFI lower in the group with, versus the one without ASDAS elevation. A significant proportion of patients with high ASDAS without BASDAI elevation had characteristics which have been associated with response to anti-TNF therapy. BASDAI<4BASDAI>4 ASDAS <2.1ASDAS >2.1ASDAS <2.1ASDAS >2.1 Age ≤40 years old33.3%35.4%23.7%22.7% BASFI≥6.54.5%5.6%5.3%35.2% 4.5-6.56.7%16.4%18.4%30.5% <4.588.8%78.0%76.3%34.3% CRP (mg/dL)≥20.7%26.0%0%14.4% 0.6-217.2%50.6%0%43.3% <0.682.1%23.3%100%42.2% HLA-B27 Positive84.9%88.7%78.1%83.9% Enthesitis Present9.7%10.8%23.7%21.0% Conclusions: If AS patients would be selected based on high ASDAS rather than elevated BASDAI, <10% of currently eligible patients would no longer be and >30% of currently not eligible patients would become eligible for anti-TNF treatment. The latter group has more characteristics that have shown to be associated with good outcome to therapy. ASDAS high disease activity may therefore be a better cut-off than BASDAI elevation. References: 1. Braun et al. Ann Rheum Dis. 2005; 65(3):316-20 2. Machado et al. Ann Rheum Dis. 2011;70(1):47-53 3. Glintborg et al. Ann Rheum Dis. 2010;69(11):2002-8. 4. Rudwaleit et al. Ann Rheum Dis. 2004;63(6):665-70. 5. Rudwaleit et al. J Rheumatol. 2009;36(4):801-8. Disclosure of Interest: N. Vastesaeger: None Declared, B. Van Der Cruyssen: None Declared, J. Mulero Grant/Research support from: Pfizer, Hoffmann La Roche, Schering Plough/MSD, Consultant for: Pfizer, Speakers Bureau: Abbott, E. Munoz-Gomariz: None Declared, P. Font: None Declared, X. Juanola: None Declared, E. Collantes: None DeclaredCitation: Annals of the Rheumatic Diseases, volume 70, supplement 3, year 2011, page 127Session: Abstract Session: Treatment of spondyloarthritis (Oral Presentations )