Managing Psoriatic Arthritis Patients Presenting with Axial Symptoms

**Background:** Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease that can involve peripheral joints, entheses, and the axial skeleton (sacroiliac joints and spine). Axial involvement occurs in 25–70% of PsA patients depending on definitions used, and is associated with worse clinical outcomes including higher disease activity, poorer functional status, and reduced quality of life. There are currently no widely accepted classification criteria for axial PsA, though a joint ASAS-GRAPPA initiative (AXIS) is underway. This narrative review discusses practical management of PsA patients presenting with axial symptoms.

**Methods:** This is a narrative review summarizing current evidence on the definition, diagnosis, and management of axial involvement in PsA. The author draws on existing literature, international guidelines (ACR/NPF 2018, EULAR 2019, GRAPPA 2021), and key clinical trials including the MAXIMISE study (secukinumab in axial PsA) and post-hoc analyses of IL-23 inhibitor trials.

**Key Results:** Axial symptoms—primarily chronic back pain (duration ≥3 months) and morning stiffness—are common but do not necessarily indicate inflammatory axial involvement. Inflammatory back pain has good sensitivity (up to 80%) but poor specificity (below 50%) for axial spondyloarthritis, and its diagnostic value is likely even lower in axial PsA. A screening study of 100 psoriasis patients with chronic back pain (onset <45 years) found that 14 were diagnosed with axial PsA and 5 with peripheral PsA alone. Imaging is essential: radiographic sacroiliitis occurs in 25–50% of PsA patients and is asymmetric in up to 70% of cases. Spinal changes in axial PsA are more often asymmetric, may involve any spinal segment (including cervical spine), and can occur without sacroiliac joint involvement—unlike primary axial SpA. MRI can detect active inflammatory changes (bone marrow oedema) and structural damage. In the MAXIMISE trial, secukinumab 300 mg and 150 mg achieved ASAS20 responses at Week 12 in 63.1% and 66.3% of axial PsA patients, respectively, versus 31.3% with placebo. Post-hoc analyses suggest potential efficacy of IL-23 inhibitors (guselkumab, ustekinumab) for axial symptoms, though prospective trials are ongoing. TNF inhibitors and IL-17 inhibitors are considered effective based on axial SpA data; JAK inhibitors (tofacitinib, upadacitinib) also show efficacy in axial SpA trials. csDMARDs (methotrexate, sulfasalazine) and systemic steroids are not recommended for axial disease. CTLA4-Ig (abatacept) and PDE-4 inhibitors (apremilast) lack evidence for axial efficacy.

**Clinical Implications:** Unexplained chronic back pain (≥3 months) in psoriasis/PsA patients, especially with onset before age 45, should trigger evaluation for axial PsA. Diagnosis requires integrated assessment of clinical, laboratory, and imaging findings—no single test is sufficient. Treatment follows a stepwise approach: NSAIDs as first-line, followed by b/tsDMARDs (TNFi, IL-17i, JAKi) for inadequate responders. Drug selection should consider extra-musculoskeletal manifestations: IL-17 inhibitors are preferred for significant psoriasis, while monoclonal TNF antibodies are preferred for inflammatory bowel disease or acute anterior uveitis. Safety considerations, including cardiovascular and malignancy risks with JAK inhibitors, must be evaluated. Regular exercise/physiotherapy is recommended alongside pharmacotherapy.