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

Abstract

BackgroundThe efficacy of corticosteroids in patients with psoriatic arthritis (PsA) and inflammatory back pain has not been studied to date. In this controlled trial, we aimed to investigate the comparative performance of corticosteroids in patients with active axial-PsA (AxPsA) versus those with active ankylosing spondylitis (AS).MethodsPatients with AxPsA and AS (naïve to biologic therapies), who not only had clinically active disease, but also had bone marrow oedema on magnetic resonance imaging of the sacroiliac joints, were recruited. Clinically active disease was defined as inflammatory back pain (fulfilling Assessment of Spondyloarthritis International Society (ASAS) expert criteria), with spinal pain score (numerical rating scale 0–10) ≥4 and Bath AS Disease Activity Index (BASDAI) score ≥4 despite taking nonsteroidal anti-inflammatory drugs. Moreover, we recruited a control group of patients with 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 the following time points: baseline, week 2, and week 4. The primary efficacy end point was mean change in Ankylosing Spondylitis Disease Activity Score (ASDAS) at week 2. Key secondary outcomes were mean change in the BASDAI, Bath Ankylosing Spondylitis Functional Index (BASFI) and Ankylosing Spondylitis Quality of Life (ASQoL) at weeks 2 and 4.ResultsIn total, 40 patients were recruited (15 with AxPsA, 15 with AS, and 10 controls). At week 2 following corticosteroid treatment, patients with AxPsA had significantly greater improvement 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, visual analogue scale spinal pain score, ASQoL and BASFI improved significantly among patients with AxPsA compared to patients with AS and controls at week 2 (p < 0.05), with this trend also largely maintained at week 4.ConclusionsAxial inflammation in patients with PsA 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.

Uveitis in spondyloarthritis

“…Axial inflammation in PsA showed a better response to intra-muscular depot corticosteroid compared with both AS and non-inflammatory back pain, with a greater Ankylosing Spondylitis Disease Acitiviy Score (ASDAS) and BASDAI improvement after 2 weeks, which was maintained until week 4. 88 …”

Back pain in psoriatic arthritis: defining prevalence, characteristics and performance of inflammatory back pain criteria in psoriatic arthritis

“…There is no widely accepted definition of axial involvement in PsA and estimates vary from 25% to 70% 2–4. Definitions of axial disease in PsA have varied and have included the presence of isolated radiographic unilateral at least grade 2 sacroiliitis scored according to the New York (NY) criteria, bilateral grade 2 or unilateral grade 3 or 4 radiographic sacroiliitis, syndesmophytes or bone marrow oedema on MRI 5. In patients with PsA with predominantly axial disease, based on data extrapolated from ankylosing spondylitis (AS), it is recommended that tumour necrosis factor inhibitors be considered for treating active axial arthritis despite non-steroidal anti-inflammatory drug (NSAID) therapy 6…”

Evaluating Inflammatory Versus Mechanical Back Pain in Individuals with Psoriatic Arthritis: A Review of the Literature

“…Notable differences exist in the morphology of syndesmophytes, the development of which is correlated with elevated CRP levels; those in PsA have a larger volume and appear to progress more randomly along the spine [69,74,91]. The finding that inflammation in patients with axPsA responds better to corticosteroids than it does in patients with radiographic axSpA further supports the argument that axPsA and concomitant radiographic axSpA and psoriasis are two distinct diseases [92].…”