Axial Involvement in Psoriatic Arthritis Save

Analysis of a Greek Psoriatic Arthritis (PsA) cohort shows that nearly one quarter of patients have axial involvement, and among them, ∼30% have isolated spinal axPsA and nr-axSpA, respectively.

Axial PsA (axPsA) was defined as PsA (CASPAR criteria) accompanied by inflammatory back pain (present or ever) and positive imaging findings of the sacroiliac joints and/or spine (MRI: active inflammation of sacroiliac joints and/or spine; X-rays: 1984 New York-criteria for radiographic sacroiliitis and/or presence of syndesmophytes in the spine). Patients were categoriezed as a.) Isolated sacroiliac joint involvement (sacroiliac axPsA) vs b) isolated involvement of the rest of the spine (spinal axPsA) or C) non-radiographic axPsA (nr-axPsA, positive MRI findings only) vs radiographic axPsA (r-axPsA, positive X-ray findings).

From 922 patients in the Greek-multicentre PsA study, 238 (26%) had axPsA. 

These axPsA patients had: 

• Less peripheral arthritis at diagnosis
• Increased HLA-B27 positivity, enthesitis and inflammatory bowel disease (IBD)
• 42% had isolated sacroiliac axPsA 
  • Sacroiliac axPsA patients were younger (OR: 0.97, 95% CI: 0.94–0.99) and had more enthesitis at diagnosis (OR: 3.37, 95% CI: 1.66–6.82).
• 32% had isolated spinal axPsA.  
• 35% had nr-axPsA 
  • more commonly females (OR: 2.59, 95% CI: 1.39–4.82) and younger (OR: 0.96, 95% CI: 0.94–0.99) compared to r-axPsA.

PsA with axial involvement is a unique PsA subset manifest as isolated SI or spinal disease or nr-axSpA. Many of these patients are women, young with associated enthesitis or IBD.