Seronegative Spondyloarthritis

Definition and classification system (NEJM 2016;374:2563)

  • Spondyloarthritis (SpA): group of inflammatory disorders that share common clinical manifestations: inflammatory spine disease, peripheral arthritis, enthesitis (see below), and extra-articular manifestations (primarily ocular and skin disease)
  • Seronegative = absence of autoantibodies
  • Subtypes: ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis (ReA), IBD-associated arthritis, juvenille SpA and undifferentiated

Epidemiology & pathogenesis (Nat Rev Rheumatol 2015;11:110)

  • Prevalence 0.5–2% worldwide; AS and non-radiographic axial SpA most common
  • HLA-B27 accounts for ~30% of attributable genetic risk but not required for diagnosis
  • Environmental factors likely critical for se, esp reactive arthritis (ie, infection)