Treatment Guideline Chart
Spondyloarthritis refers to a group of inflammatory diseases characterized by spinal & joint oligoarthritis, enthesitis, and sometimes mucocutaneous, ocular and/or cardiac manifestations.
Ankylosing spondylitis is a prototype of spondyloarthritis, particularly of the axial form.
Diagnosis of ankylosing spondylitis is definite if any of the radiological criterion is associated with at least one clinical criterion.

Ankylosing%20spondylitis Diagnosis

Physical Examination for Ankylosing Spondylitis

  • Restricted movement forward flexion of the lumbar spine monitored by Schober test
  • Limited lateral flexion and extension of the lumbar spine
  • Measurement of chest expansion to assess thoracic involvement
  • Sacroiliac inflammation is determined by direct tenderness on pressure at the joint line or Flexion, ABduction, External Rotation and Extension (FABERE) test or Gaenslen maneuver 

Laboratory Tests for Ankylosing Spondylitis

  • Laboratory findings are usually nonspecific
  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) may be elevated in some cases
  • Complete blood count shows normocytic, normochromic anemia especially in patients with very active disease or long-standing condition
  • Human leukocyte antigen (HLA)-B27 may be present in most patients with axial SpA


Diagnosis of Spondyloarthritis (SpA)

Assessment in SpondyloArthritis International Society (ASAS) Classification Criteria for Axial SpA

  • Recommended for patients with axial SpA with ≥3 months back pain and <45 years of age at the time of onset
  • Preferred diagnostic criteria for patients without radiographic sacroiliitis for early diagnosis
  • Have the highest sensitivity score compared to other criteria for spondyloarthropathies
  • Imaging arm - requires ≥1 SpA feature and sacroiliitis
    • Sacroiliitis shows positive grade 2 bilateral or grade 3-4 unilateral radiographic disease or
    • Positive acute inflammation of sacroiliac joints on magnetic resonance imaging (MRI) highly suggestive of sacroiliitis
  • Clinical arm - requires a positive HLA-B27 test and ≥2 other SpA features
  • SpA features:
    • Inflammatory back pain
    • Arthritis
    • Enthesitis (heel)
    • Dactylitis
    • Psoriasis
    • Crohn’s disease/ulcerative colitis
    • Good response to nonsteroidal anti-inflammatory drugs (NSAIDs)
    • Positive family history of SpA
    • Increased CRP
    • HLA-B27 positive
    • Uveitis
    • Alternating pelvic pain between the left and right gluteal areas

National Institute for Health and Care Excellence (NICE) Criteria for Axial SpA

  • Low back pain before the age of 45 that persists for >3 months with ≥4 of the following criteria or 3 of the following criteria plus a positive HLA-B27 test:
    • Low back pain before the age of 35 years of age
    • Waking from sleep at night because of symptoms
    • Buttock pain
    • Improves with movement
    • Improves within 48 hours of taking NSAIDs
    • 1st-degree relative with SpA
    • Current or previous arthritis
    • Current or previous enthesitis
    • Current or previous psoriasis

European Spondyloarthropathy Study Group (ESSG) Criteria

  • Inflammatory spinal pain or synovitis
    • Synovitis may be asymmetric or predominantly in the lower extremities
    • Required criteria to make the diagnosis of AS
  • And 1 or more of the following:
    • Positive family history
    • Psoriasis
    • Inflammatory bowel disease
    • Enthesopathy
    • Sacroiliitis
    • Urethritis, cervicitis, or acute diarrhea within 1 month prior to occurrence of arthritis

Amor Criteria

  • According to the Amor criteria, patients with a total score of ≥6 based on symptoms and clinical history indicates SpA
  • 1 point each
    • Lumbar or dorsal pain at night or morning stiffness of lumbar or dorsal spine
    • Buttock pain
    • Non-gonococcal urethritis or cervicitis accompanying or within 1 month before onset of arthritis
    • Acute diarrhea accompanying or within 1 month before onset of arthritis
  • 2 points each
    • Asymmetric oligoarthritis
    • Buttock pain alternately affecting the right or left buttock
    • Sausage-like toe or digit (dactylitis)
    • Heel pain or any other well-defined enthesitis
    • Iritis
    • History of psoriasis, balanitis, or inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
    • Presence of HLA-B27
    • Familial history of AS, Reiter syndrome, uveitis, psoriasis, or chronic encephalopathies
    • Good response to NSAIDs in 48 hours or relapse of pain in <48 hours upon discontinuation
  • 3 points for sacroiliitis (grade ≥2 if bilateral or grade ≥3 if unilateral)

Diagnosis of Ankylosing Spondylitis

  • Modified New York criteria (1984):
    •  Radiological criteria
      • Sacroiliitis: Grade ≥2 if bilateral or grade ≥3 if unilateral
    • Clinical criteria
      • Low back pain and stiffness for >3 months that improves with exercise, but are not relieved by rest
      • Limitation of motion of the lumbar spine in both sagittal and frontal planes
      • Limitation of chest expansion relative to normal values correlated for age and gender
    • Grading
      • Definite AS is defined when any of the radiological criterion is associated with at least 1 clinical criterion
      • Probable AS is defined if 3 clinical criteria are present or radiologic criterion is present without a clinical criteria

Diagnosis of Non-Radiographic Axial Spondyloarthritis

  • Diagnosis is supported by the presence of active inflammation of the sacroiliac joint that is best visualized by MRI
  • About 5-10% of patients with non-radiographic axial SpA, shown in several studies, will develop sacroiliitis of AS within about 2 years and about 20% after about 5 years of follow-up

Imaging for Ankylosing Spondylitis

  • X-ray is the the gold standard for assessing post-inflammatory and structural changes in axial SpA
    • Not all individuals will exhibit radiographic features, especially early in the course of the disease
    • Although useful for detecting structural changes, radiographs cannot detect inflammatory changes
    • Typical findings in X-ray of AS are bilateral sacroiliac joint involvement showing erosions in the joint line, pseudodilation, extensive subchondral sclerosis and partial ankylosis
      • Radiologic changes may result in a “bamboo spine” which is caused by bridging syndesmophytes, usually seen in late AS
  • May perform pelvic MRI in suspected AS patients with no evidence of sacroiliitis to check for inflammatory changes


Assessment for Ankylosing Spondylitis

  • Therapy of patients with AS should be tailored according to the following:
    • Current manifestations of AS (eg axial, peripheral, entheseal, extra-articular)
    • Level of current symptoms, clinical findings and prognostic indicators
    • General clinical status (eg age and gender, comorbidities, concomitant therapy, psychosocial factors)
  • Frequency of assessments (eg patient history with use of questionnaires, clinical parameters, laboratory tests, imaging) should be decided based on course of symptoms, severity, and treatment
  • Referral to a rheumatologist is important for proper assessment, management and monitoring of AS patients

Assessment in SpondyloArthritis International Society (ASAS) Core Set

  • Group of core domains assessed for treatment response and disease activity
  • Includes assessment of function, pain, patient’s global assessment, stiffness, spinal mobility, peripheral joints and entheses, acute phase reactants (APRs), fatigue, and radiographs aided by the following instruments:
    • Physical function: Bath Ankylosing Spondylitis Functional Index (BASFI)
    • Pain: Numerical rating scale/visual analogue scale (NRS/VAS) during the past week, of the spine at night, and identified from AS
    • Patient global assessment: NRS/VAS of the past week
    • Spinal mobility: Chest expansion, modified Schober, occiput to wall distance, cervical rotation and lateral spinal flexion or Bath Ankylosing Spondylitis Metrology Index (BASMI)
    • Stiffness: NRS/VAS duration of morning stiffness of the spine in the past week
    • Peripheral joints and entheses: Number of swollen joints (44 joints count), enthesitis score [eg Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), Berlin, or San Francisco]
    • Acute phase reactants (APRs): ESR or CRP
    • Fatigue: Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)
    • Radiographs: Used as a measure of outcome of pharmacotherapy rather than disease activity, includes X-ray of anteroposterior, lateral lumbar, lateral cervical spine, and pelvic area to visualize the sacroiliac joints and hips

Other Disease Activity Score

  • Ankylosing Spondylitis Disease Activity Score - CRP (ASDAS-CRP) combines patient-reported outcomes and APRs (CRP or ESR)
    • Better index than BASDAI because it correlates better with level of disease activity

Criteria for Response

  • Active AS is defined as AS ≥4 weeks and BASDAI ≥4 as assessed by a rheumatologist
  • Assessment in SpondyloArthritis International Society (ASAS) 20
    • Improvement of ≥20% and  ≥1 unit on a scale of 10 in at least 3 of the following 4 domains: Patient global, pain, function, inflammation
    • No worsening of ≥20% and ≥1 unit on a scale of 10 in the remaining domain
  • ASAS 40
    • Improvement of ≥40% and ≥2 units on a scale of 10 in at least 3 of the following 4 domains: Patient global, pain, function, inflammation
    • No worsening at all in remaining domain
  • ASAS 5/6
    • Improvement of ≥20% in at least 5 of the following 6 domains: Patient global, pain, function, inflammation, CRP, spinal mobility
  • ASAS partial remission
    • ≤2 units on a scale of 10 in each of the following 4 domains: Patient global, pain, function, inflammation
Editor's Recommendations
Special Reports