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


Muhammad Haroon (1), Muddassar Ahmad (1), Nouman Baig (2), Olivia Mason (3), John Rice (2), Oliver FitzGerald (4)


1. Division of Rheumatology, Department of Medicine, University Hospital Kerry, Tralee; 2. Department of Orthopaedics, University Hospital Kerry, Tralee, Ireland; 3. CSTAR, University College Dublin, Ireland; 4. Department of Rheumatology, St Vincent’s University Hospital, Dublin, Ireland


The efficacy of corticosteroids in psoriatic arthritis (PsA) patients with inflammatory back pain has not been studied to date. Most of the treatment response data about axial involvement in PsA come from ankylosing spondylitis (AS) studies


In this controlled trial, we aimed to investigate the comparative performance of corticosteroids for active axial-PsA (AxPsA) versus those with active ankylosing spondylitis (AS).


AxPsA and AS patients (naïve to biologic therapies), who not only had clinically active disease, but also had bone marrow oedema on MRI of sacroiliac joints were recruited. Clinically active disease was defined as patients with inflammatory back pain (fulfilling ASAS Expert Criteria)13, with spinal pain score (numerical rating scale 0-10) of ≥4 and BASDAI score ≥4 despite taking NSAIDS. Moreover, we recruited a control group of non-inflammatory lower back pain (table-1). All patients received a single, intra-muscular dose of depot corticosteroid injection (Triamcinolone Acetonide 80mg) 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.


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 also when compared to controls (p<0.001). At week-4, similar significant trend of ASDAS improvement was seen among AxPsA patients compared to AS patients (1.09 ± 0.32 vs. 0.77 ± 0.27, p=0.007) and controls (p<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 (Figure-1,2).


Axial inflammation in PsA patients 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.