Background In cross-sectional studies patients with non-radiographic axial SpA (nr-axSpA) and ankylosing spondylitis (AS) demonstrated similar characteristics regarding clinical signs of disease activity [1, 2]. Further, patients with active nr-axSpA did not differ from AS patients with respect of response rates to anti tumour necrosis factor (TNF) α treatment [3, 4]. It is however not known whether nr-axSpA is associated with higher probability of “spontaneous” remission/low disease activity state if not treated with a TNF-blocker.

Objectives To investigate the rates of remission/low disease activity states over two years without anti-TNF treatment in patients with nr-axSpA and AS who were candidates for anti-TNF treatment at baseline.

Methods In total, 210 patients with early axSpA (115 with AS according to the modified New York criteria and symptom duration ≤10 years, and 95 with nr-axSpA and symptom duration ≤5 years) from the German Spondyloarthritis Inception Cohort (GESPIC) were evaluated at baseline and every 6 months thereafter till 2 years. Patients with nr-axSpA were considered to be candidates for anti-TNF therapy at baseline if they had BASDAI ≥4 and elevated C-reactive protein (CRP, >6 mg/l). Similar criteria were applied for AS patients in order to have a comparable group. Patients who received at least one prescription of a TNF blocker were excluded. The following definitions for low disease activity were applied: BASDAI<4, BASDAI<4 and normal CRP, BASDAI ≤2, ASDAS inactive disease (<1.3). Proportions of patients achieving low disease activity at year 2 or at least at 2 time points during the follow-up were calculated.

Results Eleven patients (11.6%) with nr-axSpA and 28 patients (24.3%) with AS were considered to be candidates for the anti-TNF therapy at baseline due to elevated BASDAI and CRP. One nr-axSpA patient and 6 AS patients received anti-TNF treatment during the follow-up and were excluded. Remaining patients in both groups (10 with nr-axSpA and 22 with AS) received conventional therapy including physiotherapy, NSAIDs, DMARDs, and steroids.

At year 2 BASDAI<4 was achieved by 50% of nr-axSpA patients and 38% AS patients, BASDAI<4 and normal CRP by 29% and 16%, BASDAI≤2 by 17% and 19%, and ASDAS inactive disease by 16.7% and 6.3% of the patients, respectively.

BASDAI<4 at at least 2 time points during 2 years of the follow-up was achieved by 57% of nr-axSpA and by 40% of AS patients, BASDAI<4 and normal CRP by 25% and 13%, BASDAI≤2 by 13% and 13%, and ASDAS inactive disease by 25% and 0% of nr-axSpA and AS patients, respectively. All differences were statistically non-significant.

Conclusions Only a small proportion of patients (<25%) with nr-axSpA and AS reached a stricter definition of low disease activity over two years of follow-up without TNF-blocker treatment. The rates were numerically lower in AS if a combined definition of low disease activity with inclusion of CRP was used.

References

1. Rudwaleit M, et al. Arthritis Rheum. 2009;60:717-27. 2. Kiltz U, et al. Arthritis Care Res (Hoboken). 2012;64:1415-22. 3. Song IH, et al. Ann Rheum Dis. 2013;72:823-5. 4. Landewé R, et al. Ann Rheum Dis. 2014;73:39-47.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.3598