SAT0342 Inflammatory back pain in psoriatic arthritis is significantly more responsive to corticosteroids compared to back pain in ankylosing spondylitis: a prospective, open-labelled, controlled pilot study
Authors: M. Haroon, M. Ahmad, N. Baig, O. Mason, J. Rice, O. FitzGerald
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Inflammatory spinal disease is one of three inflammatory musculoskeletal manifestations which frequently occur in PsA. There is very limited data about the axial involvement in PsA, especially as regards treatment, with treatment guidelines based largely on data from AS trials. The efficacy of corticosteroids in PsA patients with inflammatory back pain has not been studied to date. <h3>Objectives</h3> In this controlled trial, we aimed to investigate the comparative performance of corticosteroids for active axial-PsA (AxPsA) versus those with active AS. <h3>Methods</h3> PsA patients (fulfilling CASPAR criteria), and AS as per the 1984 Modified New York Criteria, were suitable for inclusion. Among them, patients with active AxPsA and active AS ((naïve to biologic therapies) were recruited. The active disease was defined as patients with inflammatory back pain, with spinal pain score of ≥4 and BASDAI score ≥4 despite taking NSAIDS. Furthermore, only those AxPsA and AS patients with an MRI proven sacroiliac joint bone marrow oedema (MRI of sacroiliac joints performed within the 6 months prior to recruitment) were considered for inclusion. Hence, all recruited patients with AxPsA and AS had not only clinically active disease, but also had bone marrow oedema on MRI of sacroiliac joints. Moreover, we recruited a control group of non-inflammatory lower back pain. All patients received a single, intra-muscular dose of depot corticosteroid injection (Triamcinolone Acetonide 80 mg) at baseline. The intra-muscular corticosteroid option was used to overcome any drug compliance issues. Clinical outcome assessments were made at following time points: baseline, week-2, and week-4. The primary efficacy end point was the mean change in Ankylosing Spondylitis Disease Activity Score (ASDAS) at week-2. Key secondary outcome were the mean change of BASDAI, BASFI and ASQoL at week-2 and week-4. <h3>Results</h3> In total, 40 patients were recruited – AxPsA=15, AS=15, control=10. At week-2 following corticosteroid treatment, patients with AxPsA had significantly higher improvements in the mean ASDAS compared to patients with AS (1.43±0.39 vs. 1.03±0.30, p=0.004), and the same was the case when compared to controls (p&lt;0.001, table-2, figure-1). At week-4, AxPsA patients also showed significantly higher improvements in the mean ASDAS compared to both AS patients (1.09±0.32 vs. 0.77±0.27, p=0.007) and controls (p&lt;0.001). Similarly, the mean BASDAI, VAS spinal pain score, ASQoL and BASFI improved significantly among AxPsA patients compared to AS patients and controls at week-2, with this trend also largely maintained at week-4 <h3>Conclusions</h3> Axial inflammation in PsA potentially responds significantly better to corticosteroids than in patients with AS. This furthers the argument and adds to the growing evidence that AxPsA and AS are distinct entities. Future studies should further investigate the use of corticosteroids and of sDMARD usage among patients with active IBP in PsA. <h3>Disclosure of Interest</h3> M. Haroon Grant/research support from: Abbie, Pfizer, Speakers bureau: Abbie, Pfizer, UCB, M. Ahmad: None declared, N. Baig: None declared, O. Mason: None declared, J. Rice: None declared, O. FitzGerald: None declared