Nearly a third of patients with psoriasis who attend dermatology clinics have undiagnosed psoriatic arthritis (PsA). PsA has been associated with joint erosions even after treatment with disease-modifying antirheumatic drugs (DMARDs).
Assessments included spinal pain score (numerical rating scale, 0-10), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Ankylosing Spondylitis Quality of Life (ASQoL), Ankylosing Spondylitis Disease Activity Score (ASDAS), patient global assessment (numeric rating scales, 0-10), number of swollen joints (66/68-joint score), and number of tender entheseal sites (Leeds Enthesitis Index).
When subjects with AS were compared with controls at week 2 of the corticosteroid challenge, there was minimal improvement in ASDAS (1.02 ± 0.30 vs 0.81 ± 0.25, P = .077), but at week 4 there were no significant improvement in ASDAS (0.76 ± 0.27 vs 0.74 ± 0.22, P = .79).
The bottom line: Corticosteroids are far more effective in treating inflammatory back pain in patients with axial PsA than in patients with AS.