Spondyloarthritis (SpA)

Meridith Balbach

Background

  • Seronegative spondyloarthropathy: family of disorders characterized inflammatory arthritis, enthesitis, and absence of serologic markers
  • Includes: ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis (PsA), IBDassociated arthritis, undifferentiated spondylarthritis
  • Often further classified by either peripheral or axial involvement
  • HLA-B27 is linked to disease susceptibility (strongest link to AS); however, AS can occur in absence of the gene (~10%) and only ~3% of HLA-B27 positive subjects develop AS

Ankylosing Spondylitis

Krissie Lobon

Presentation

  • Onset typically before age 30 (often teens to 30s)
  • MSK: insidious inflammatory back pain (hallmark), alternating buttock pain with sacroiliac involvement, enthesitis
  • Peripheral arthritis may occur and often involves larger joints such as hips, knees, and ankles.
  • Extra-articular: acute anterior uveitis, psoriasis, IBD
  • Typically encompasses 4 of 5 features: age of onset <40 years, insidious onset, improvement with exercise, no improvement with rest, pain at night (improvement upon arising)

Evaluation

  • Labs: No specific laboratory tests for AS
    • HLA-B27 is often present (90% of white patients; lower in other groups), though not necessary for diagnosis
    • Elevated CRP and ESR in 50-70% of pts with active AS and less frequently elevated in pts with non-radiographic subtype
  • Imaging
    • X-ray and MRI: joint space narrowing and sclerosis secondary to erosive changes in SI joint, pelvis, and/or spine; bony ankylosis /fusion can eventually be seen in progressive disease
    • MRI can reveal inflammatory changes (bone marrow edema); helpful in non-radiographic (X-ray negative) subtype
  • Classification criteria is used for diagnostic purposes
    • Assessment of SpondyloArthritis International Society Criteria (2011): ≥3mos back pain before 45yo and either sacroiliitis on imaging + ≥1 other axial spondyloarthritis (SpA) feature OR HLA-B27 positive + ≥2 SpA features
    • SpA features: arthritis, dactylitis, enthesitis, psoriasis, IBD, uveitis, FHx, HLA-B27

Management

  • Initial therapy: NSAIDs for symptomatic axial spondyloarthropathies. Occasionally NSAIDs alone improve symptoms and are the only medications required
  • Refractory symptoms: 1st line TNF inhibitors followed by IL-17 inhibitors (second option, most effective in pts with concomitant psoriasis). JAK inhibitors also approved.
  • Physical therapy: intensive rehabilitation and exercise improve mobility and symptoms
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