Ankylosing%20spondylitis Diagnosis

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

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

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